Fix Optional["ForwardRef"] rewriting

[mhils]

Optional["ForwardRef"] currently requires two pyupgrade calls to be fully rewritten. Here's a minimal example:

$ echo "from __future__ import annotations; from typing import Optional; x: Optional['str']" > repro.py

$ pyupgrade --py39-plus repro.py; cat repro.py
Rewriting repro.py
from __future__ import annotations; from typing import Optional; x: Optional[str]

$ pyupgrade --py39-plus repro.py; cat repro.py
Rewriting repro.py
from __future__ import annotations; from typing import Optional; x: str | None

The problem here is that typing_pep604.py bails if it encounters a forward annotation (#567). This PR adjusts the check to guess ahead if annotations will be dequoted by typing_pep563.py.

I guess there's an argument to be made that forward refs and from __future__ import annotations in the same file aren't best practice to begin with, but I've encountered that in real-world code and figured I'd send a fix. No hard feelings if you consider this a wontfix. :)

[asottile]

while it probably doesn't actually matter in practice -- the 'annotations' in check is very cheap and should probably come before the computation for forward annotations

[mhils]

Good point, fixed. I've kept the has_forward_annotation variable for readability, but that is subjective. Let me know if you want me to make it a single big if statement. :)

[asottile]