CSV import: Generate positive UID for .translation and follow renames

[lyuma]

Fixes #103118

Mask with INT64_MAX to avoid negative UIDs which cause bugs.
If the generated .translation UID is already in use (renamed), overwrite that file instead.

[KoBeWi]

Looks correct, but the comments above should be addressed.

[lyuma]

Added an if to avoid a redundant set_uid. The way I'm resolving the conflict here is to prefer saving to whatever path has the matching uid, rather than generating a new uid. I think the usecase is users might move their generated .translation files to a folder, and that should be okay now since the UID for a given .translation is deterministic.

Re: real collision, we're talking 1 in 2^64 per file. I think the probability is something like if every human on earth made a few Godot projects for the next 100 years, you might get one collision ever. My opinion is this is not worth worrying about, since the consequence of a UID collision in the worst case is also not too bad. Also, this risk affects all code using UIDs, not just translation.

Rather than add a special case for 1 in 2^64 collision, we should change ResourceUID or ResourceSaver to emit an error if a collision is detected or uid:// or any other type of UID mismatch happens, which would have caught this bug much sooner.

[akien-mga]

Thanks!

[MarianoGnu]

oh, .translation files generates .uid files? these files are tipically ignored in git because they are autogenerated from csv 🤔 but makes total sense to ensure the uid remains unique across different devices never tought of it👍