Add `fixModifiers.gradle` to run after `check` task.
The `RedundantModifierChecker` doesn't catch all errors at once.
We need run `check -> fixModifiers` pair several times to reach `SUCCESSFUL`.
The `fixThis` has been ported from the SA, but without applying.
* Polishing for `fixModifiers.gradle`
* Fix all redundant modifier with the `fixModifiers.gradle`
NOTE: Since all these task modify files on Windows we have to run them with the `-Dfile.encoding=UTF-8`.
Otherwise they are read and write with the Windows default `cp1251` making them incompatible with Unix system.
c2954881ad