fix: recognize global String substring lookups (#1734)

* fix: prevent false positive in js-set-map-lookups for String().includes()

- Add check to ensure String() refers to global constructor, not shadowed variable
- Add regression tests for the String() constructor case
- Add corpus regression test file

Closes #1733

Co-authored-by: Skosh <skoshx@users.noreply.github.com>

* fix: recognize global String substring lookups

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Co-authored-by: Cursor Agent <cursoragent@cursor.com>
Co-authored-by: Skosh <skoshx@users.noreply.github.com>
Co-authored-by: Aiden Bai <aiden@million.dev>