PY-17183 Heuristically determine when incomplete docstring captures another declaration

To do so I search for the line inside a docstring that starts with
either "def " or "class " and has indentation less than that of opening
docstring quotes.

python/testData/editing/enterDocstringStubWhenClassDocstringBelow.after.py

@@ -0,0 +1,12 @@
+def f():
+    """
+    
+    Returns:
+
+    """
+    
+    
+class Class:
+    """
+    bar
+    """

python/testData/editing/enterDocstringStubWhenClassDocstringBelow.py

@@ -0,0 +1,8 @@
+def f():
+    """<caret>
+    
+    
+class Class:
+    """
+    bar
+    """

python/testData/editing/enterDocstringStubWhenFunctionDocstringBelow.after.py

@@ -0,0 +1,12 @@
+def f():
+    """
+    
+    Returns:
+
+    """
+    
+    
+def g():
+    """
+    bar
+    """

python/testData/editing/enterDocstringStubWhenFunctionDocstringBelow.py

@@ -0,0 +1,8 @@
+def f():
+    """<caret>
+    
+    
+def g():
+    """
+    bar
+    """

python/testData/editing/enterNoDocstringStubWhenCodeExampleInDocstring.after.py

@@ -0,0 +1,15 @@
+def f():
+    """
+    
+    Monospaced ``func`` and func
+
+    Example:
+
+        ::
+        
+            def func():
+                pass
+
+            class Class():
+                pass
+    """

python/testData/editing/enterNoDocstringStubWhenCodeExampleInDocstring.py

@@ -0,0 +1,14 @@
+def f():
+    """<caret>
+    Monospaced ``func`` and func
+
+    Example:
+
+        ::
+        
+            def func():
+                pass
+
+            class Class():
+                pass
+    """