Use `StrCollection` in more places

[clokep]

Using a Sequence[str] or Collection[str] is bad since a str also fits those and you usually want this to refer to a Set[str], List[str], Tuple[str, ...], etc.

In #14716 @reivilibre added a StrCollection type which we can re-use for this.

This has bit us a few times in the past but I'm failing to find references at the moment.

It would be good to audit Sequence[str] and Collection[str] and see if any of those should be updated.

[clokep]

I was using grep -rE "(Collection|Sequence)\[str\]" <path> to attempt to find these.

[clokep]

I'm assuming Collection[bytes] and Sequence[bytes] have the same issue? I couldn't think of any other potential examples though?

[clokep]

I'm assuming Collection[bytes] and Sequence[bytes] have the same issue? I couldn't think of any other potential examples though?

Or rather bytes would match Collection[int], etc. I'm not sure we need to "protect" against this as it seems like a less likely mistake to make.

[clokep]

I think we also want to look at Iterable[str] and Container[str] FTR, so the grep might now be

grep -rE "(Collection|Sequence|Iterable|Container)\[str\]" ....