Add reverse UID cache

[KoBeWi]

Fixes #75617

This PR introduces a reverse UID cache, i.e. HashMap of path -> UID. It's only used at runtime. The downside is that it basically doubles memory usage of UID cache (not sure how much is that a problem), but the alternative is doing a reverse lookup on the base cache, which would involve iterating every entry; not very efficient.

[sodaJar]

Finally this is being fixed

[bruvzg]

The downside is that it basically doubles memory usage of UID cache (not sure how much is that a problem)

Should not be an issue, UID cache won't be large enough to be noticeable.

[Repiteo]

Thanks!