Fix LSP.plugin.core.typing with py38

[jfcherng]

Since we are now in py38, we don't need most of type polyfills.

# noqa: F401 is to suppress import but no used linter warnings.

[predragnikolic]

Hello,

I tested this, and it looks like the NotRequired needs more work.

Some LSP-jdtls, LSP-julia, LSP-volar import NotRequired from LSP.plugin.core.typing.

This PR breaks them:
TypeError: <class 'LSP.plugin.core.typing.NotRequired'> is not a generic class

[jfcherng]

TypeError: <class 'LSP.plugin.core.typing.NotRequired'> is not a generic class

@predragnikolic Wondering whether 1856443 (#2456) works for that.

[predragnikolic]

It works.

Ideally LSP-* plugins can now import types from typings or typing_extensions instead of importing from LSP.plugins.core.typing. But LSP.plugins.core.typing can exist as long as there is something using it.

And instead of List, Dict, we can use list, dict, tuple,... from __future__ import annotations

[jfcherng]

Ideally LSP-* plugins can now import types from typings or typing_extensions instead of importing from LSP.plugins.core.typing. But LSP.plugins.core.typing can exist as long as there is something using it.

And instead of List, Dict, we can use list, dict, tuple,... from __future__ import annotations

Yeah. That's what I encountered. When using lsp_utils, get complaints like tuple is not compatible with Tuple, which is imported by lsp_utils from LSP.plugins.core.typing.

[predragnikolic]

Tested, works.

[predragnikolic]

Thanks!