feat(typing): add type hints to hooks

[copalco]

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[CaselIT]

this seems to include https://github.com/falconry/falcon/pull/2171. I'll get to this once the other one is merged (I hope to merge it soon)

[CaselIT]

Since we dropped 3.7 we can probably avoid having everything inside a type check block. Will do

[CaselIT]

Maybe it would be nice if it is importable without TYPE_CHECKING too? Should we document any aliases?

For the moment I mentioned in the v4 chance log that any type alias should be treated as private, since it can change between releases.

I think once we are adding typing we can do a bit of cleanup and maybe provide a public set to aliaes