Import __future__ annotations

[deathaxe]

This commit...

1. adds from __future__ import annotations to each relevant module in order to enable language level type annotation support.
2. as a result most quotation marks can be removed from type annotations.

[predragnikolic]

this PR triggers an error in LSP-elm ->

  File "/Users/predrag/Library/Application Support/Sublime Text/Packages/LSP-elm/types.py", line 29, in <module>
    'destination': NotRequired[MoveDestination]
  File "/Users/predrag/Library/Application Support/Sublime Text/Lib/python38/typing_extensions.py", line 2071, in __getitem__
    item = typing._type_check(parameters,
  File "./python3.8/typing.py", line 149, in _type_check
TypeError: NotRequired accepts only a single type. Got {}.
reloading plugin LSP-elm.types

[predragnikolic]

I will fix this in LSP-elm,
but that error can be also happen in other LSP-*, although I have most checked out locally.

EDIT:
With #2456 the error no longer happens.

[predragnikolic]

Thanks!