Illegal reflective operation warning from kotlin-compiler-embeddable

[petertrr]

I think under this issue we can also investigate problem with extra warnings from kotlin
Seems, it should be fixed (youtrack, stackoverflow) in kotlin 1.5

Originally posted by @kgevorkyan in #971 (comment)

[orchestr7]

All compilation warnings should be fixed under this issue

[petertrr]

@akuleshov7 we don't have any compilation warnings, because we've enabled -Werror long ago under #781

This issue is about runtime warning which appears to be caused by incorrect usage of reflection deep inside kotlin-compiler. It needs some investigation, but it'll probably have to be resolved on their side.

[nulls]

Tested, it was fixed. Added a checking on WARNING in diktat cli output in tests