PY-53104 Support PEP 673 typing.Self type

GitOrigin-RevId: 8efc65725580510dc3e9a93e1242e1a69032c8f1

python/testData/completion/onListSelf.py

@@ -0,0 +1,9 @@
+from typing import Self
+
+class A:
+    def foo(self) -> list[Self]:
+        ...
+class B(A)
+    def bar(self) -> Self:
+        ...
+B().foo()[0].<caret>

python/testData/completion/onListSelfInNestedClass.py

@@ -0,0 +1,10 @@
+from typing import Self
+
+class OuterClass:
+    class A:
+        def foo(self) -> list[Self]:
+            ...
+    class B(A)
+        def bar(self) -> Self:
+            ...
+OuterClass.B().foo()[0].<caret>

python/testData/completion/onSelf.py

@@ -0,0 +1,9 @@
+from typing import Self
+
+class A:
+    def foo(self) -> Self:
+        ...
+class B(A)
+    def bar(self) -> Self:
+        ...
+B().foo().<caret>

python/testData/completion/onSelfInsideClassFunction.py

@@ -0,0 +1,8 @@
+from typing import Self
+
+
+class HasNestedFunction:
+    x: int = 42
+
+    def foo(self, inner_self: Self) -> None:
+        print(inner_self.<caret>)

python/testData/completion/onSelfInsideClassFunctionNestedFunction.py

@@ -0,0 +1,12 @@
+from typing import Self
+
+
+class HasNestedFunction:
+    x: int = 42
+
+    def foo(self) -> None:
+        def nested(z: int, inner_self: Self) -> Self:
+            print(inner_self.<caret>)
+            return inner_self
+
+        nested(42, self)