GH-19: [Python] Fix unresolved-global (#39)

* Add py.typed file to signify that the library is typed

See the relevant PEP https://peps.python.org/pep-0561

* Prepare `pyarrow-stubs` for history merging

MINOR: [Python] Prepare `pyarrow-stubs` for history merging

Co-authored-by: ZhengYu, Xu <zen-xu@outlook.com>

* Add `ty` configuration and suppress error codes

* One line per rule

* Add licence header from original repo for all `.pyi` files

* Revert "Add licence header from original repo for all `.pyi` files"

This reverts commit 1631f39.

* Prepare for licence merging

* Exclude `stubs` from `rat` test

* Add Apache licence clause to `py.typed`

* Reduce list

* Add `ty` as a step in the action

* Run in the correct directory

* Remove `check` from `pip`

* Fix `unresolved-reference` error

* Revert "Fix `unresolved-reference` error"

This reverts commit 7ee3d2f.

* Fix unresolved-global

---------

Co-authored-by: Patrick J. Roddy <patrickjamesroddy@gmail.com>

Author: rok

python/pyarrow/tests/test_flight.py

@@ -1118,7 +1118,7 @@ def test_client_wait_for_available():
     server = None
 
     def serve():
-        global server
+        nonlocal server
         time.sleep(0.5)
         server = FlightServerBase(location)
         server.serve()

python/scripts/run_emscripten_tests.py

@@ -114,7 +114,7 @@ def end_headers(self):
 
 
 def run_server_thread(dist_dir, q):
-    global _SERVER_ADDRESS
+    global _SERVER_ADDRESS  # type: ignore[unresolved-global]
     os.chdir(dist_dir)
     server = http.server.HTTPServer(("", 0), TemplateOverrider)
     q.put(server.server_address)