(cherry picked from commit a2a406a1)

[gui-test] ScriptGenerator refactoring. Remove commented code, extract internal classes, fix yellow code

previously known as IndexTestGenerator.scala

remove duplicates, ensure inner classes are processed correctly

PersistentHashMap (IDEA-173669)

This reverts commit 559143fd which was a fix for IDEA-108316

VcsRootDetector is not fast enough to be run in EDT thus IDEA-174636.
The limit will be removed again after IDEA-174636 is fixed,
i.e. when the root scanning in the Settings is made async.

following IDEA-CR-22197