Removed test filtering in JetQuickFixTest.
Replaced if-check with assert.
EA-41429 - CCE: SpecifyTypeExplicitlyAction.invoke

Implemented custom invoke() in SpecifyTypeExplicitlyFix.
Removed unnecessary subclassing.
Renamed class.
Renamed class.
Matching test files by regex instead of extension.
Regenerated tests.
Extracting test name from regex matcher.
Refactored single-file quickfix test to generated tests framework.
Refactored multi-file quickfix test to generated tests framework.
Simplified test a bit.