fix(core): performance improvements

[omer-feinberg-island]

Small twicks for significant performance improvements:

1. searching visited identifiers in a set rather then an array
2. more importantly - finding refs only for unvisited identifiers

Tested on a large monorepo, got a consistent 60% time lose for large commits.

[EladBezalel]

This is great! I'll run tests locally and get this in
Aren't there any tests to be added?

[Copilot]

Copilot reviewed 1 out of 1 changed files in this pull request and generated no comments.

Comments suppressed due to low confidence (1)

libs/core/src/true-affected.ts:283

• [nitpick] The local variable 'visited' holds a Set of identifier names which might be unclear; consider renaming it to 'visitedSet' for improved readability.

const visited = visitedIdentifiers.get(path)!;

[EladBezalel]

closing in favor of a new PR from a branch instead of main