Vendor debugpy for VS Code attach debugging

Bundles debugpy 1.7.0 directly in python/ so "Maya: Attach (debugpy)"
works with no per-machine pip install step. Installed via Maya 2022's
own pip so it resolved a version actually compatible with Python 3.7
(Maya 2022's interpreter), then verified import + listen() succeeds
under all three target Maya Python versions (3.7/3.9/3.10).

Also fixes a latent __file__-under-exec() bug in
start_debug_server.py (same pitfall as Maya's own plugin loader,
never hit until this exercised it) and corrects the README's Maya
Python version claim -- 2022 ships Python 3.7, not 3.9 as previously
stated, which was never independently verified until now.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

python/debugpy/_vendored/pydevd/tests/test_pyserver.py

@@ -0,0 +1,155 @@
+import sys
+from _pydev_bundle._pydev_saved_modules import thread
+import pycompletionserver
+import socket
+from urllib.parse import quote_plus
+
+start_new_thread = thread.start_new_thread
+
+BUILTIN_MOD = 'builtins'
+
+
+def send(s, msg):
+    s.send(bytearray(msg, 'utf-8'))
+
+
+import unittest
+
+
+class TestCPython(unittest.TestCase):
+
+    def test_message(self):
+        t = pycompletionserver.CompletionServer(0)
+
+        l = []
+        l.append(('Def', 'description'  , 'args'))
+        l.append(('Def1', 'description1', 'args1'))
+        l.append(('Def2', 'description2', 'args2'))
+
+        msg = t.processor.format_completion_message(None, l)
+
+        self.assertEqual('@@COMPLETIONS(None,(Def,description,args),(Def1,description1,args1),(Def2,description2,args2))END@@', msg)
+        l = []
+        l.append(('Def', 'desc,,r,,i()ption', ''))
+        l.append(('Def(1', 'descriptio(n1', ''))
+        l.append(('De,f)2', 'de,s,c,ription2', ''))
+        msg = t.processor.format_completion_message(None, l)
+        self.assertEqual('@@COMPLETIONS(None,(Def,desc%2C%2Cr%2C%2Ci%28%29ption, ),(Def%281,descriptio%28n1, ),(De%2Cf%292,de%2Cs%2Cc%2Cription2, ))END@@', msg)
+
+    def create_connections(self):
+        '''
+        Creates the connections needed for testing.
+        '''
+        server = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+        server.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
+        server.bind((pycompletionserver.HOST, 0))
+        server.listen(1)  # socket to receive messages.
+
+        t = pycompletionserver.CompletionServer(server.getsockname()[1])
+        t.exit_process_on_kill = False
+        start_new_thread(t.run, ())
+
+        s, _addr = server.accept()
+
+        return t, s
+
+    def read_msg(self):
+        finish = False
+        msg = ''
+        while finish == False:
+            m = self.socket.recv(1024 * 4)
+            m = m.decode('utf-8')
+            if m.startswith('@@PROCESSING'):
+                sys.stdout.write('Status msg: %s\n' % (msg,))
+            else:
+                msg += m
+
+            if msg.find('END@@') != -1:
+                finish = True
+
+        return msg
+
+    def test_completion_sockets_and_messages(self):
+        t, socket = self.create_connections()
+        self.socket = socket
+
+        try:
+            # now that we have the connections all set up, check the code completion messages.
+            msg = quote_plus('math')
+            send(socket, '@@IMPORTS:%sEND@@' % msg)  # math completions
+            completions = self.read_msg()
+            # print_ unquote_plus(completions)
+
+            # math is a builtin and because of that, it starts with None as a file
+            start = '@@COMPLETIONS(None,(__doc__,'
+            start_2 = '@@COMPLETIONS(None,(__name__,'
+            if ('/math.so,' in completions or
+                '/math.cpython-33m.so,' in completions or
+                '/math.cpython-34m.so,' in completions or
+                'math.cpython-35m' in completions or
+                'math.cpython-36m' in completions or
+                'math.cpython-37m' in completions or
+                'math.cpython-38' in completions or
+                'math.cpython-39' in completions or
+                'math.cpython-310' in completions or
+                'math.cpython-311' in completions
+                ):
+                return
+            self.assertTrue(completions.startswith(start) or completions.startswith(start_2), '%s DOESNT START WITH %s' % (completions, (start, start_2)))
+
+            self.assertTrue('@@COMPLETIONS' in completions)
+            self.assertTrue('END@@' in completions)
+
+            # now, test i
+            msg = quote_plus('%s.list' % BUILTIN_MOD)
+            send(socket, "@@IMPORTS:%s\nEND@@" % msg)
+            found = self.read_msg()
+            self.assertTrue('sort' in found, 'Could not find sort in: %s' % (found,))
+
+            # now, test search
+            msg = quote_plus('inspect.ismodule')
+            send(socket, '@@SEARCH%sEND@@' % msg)  # math completions
+            found = self.read_msg()
+            self.assertTrue('inspect.py' in found)
+            for i in range(33, 100):
+                if str(i) in found:
+                    break
+            else:
+                self.fail('Could not find the ismodule line in %s' % (found,))
+
+            # now, test search
+            msg = quote_plus('inspect.CO_NEWLOCALS')
+            send(socket, '@@SEARCH%sEND@@' % msg)  # math completions
+            found = self.read_msg()
+            self.assertTrue('inspect.py' in found)
+            self.assertTrue('CO_NEWLOCALS' in found)
+
+            # now, test search
+            msg = quote_plus('inspect.BlockFinder.tokeneater')
+            send(socket, '@@SEARCH%sEND@@' % msg)
+            found = self.read_msg()
+            self.assertTrue('inspect.py' in found)
+#            self.assertTrue('CO_NEWLOCALS' in found)
+
+        # reload modules test
+#        send(socket, '@@RELOAD_MODULES_END@@')
+#        ok = self.read_msg()
+#        self.assertEqual('@@MSG_OK_END@@' , ok)
+#        this test is not executed because it breaks our current enviroment.
+
+        finally:
+            try:
+                sys.stdout.write('succedded...sending kill msg\n')
+                self.send_kill_msg(socket)
+
+#                while not hasattr(t, 'ended'):
+#                    pass #wait until it receives the message and quits.
+
+                socket.close()
+                self.socket.close()
+            except:
+                pass
+
+    def send_kill_msg(self, socket):
+        socket.send(pycompletionserver.MSG_KILL_SERVER)
+