+ some more classes to opt in
+ declare one more excuse, update existing excuses
+ unblock ImplicitlyDeclaredClassesTest.testGH3137b()
  - test execution hangs - in run.javac mode infinitely

+ incomplete work on
  - SwitchExpressionYieldTest
  - SwitchPatternTest

Fixes https://github.com/eclipse-jdt/eclipse.jdt.core/issues/386