toRealPath considered harmful #14480
Description
Almost all uses of toRealPath are better done with SourceAccessor, to not make local store / local file system assumptions for no good reason.
After these usages are gotten rid of, toRealPath should become just a method on LocalFSStore, the interface for which is at is actually meaningfully define. All remaining usages should be able to cope with that.
Labeling "good first issue" because individual usages are fairly easy to clean up with small PRs. It is only the final step of moving the method to LocalFSStore that will be slightly more involved. Examples of such cleanups include #14204, #14249, and #14475.