Fallthrough to default is not acceptable according to JEP 406. This patch eliminates the default cases from a special case rules and leaves only `case null` as the only special case rule.
GitOrigin-RevId: 06c865f92fed01a41c5c87e1aa0a852acb3e7ee0
Add the fix to properly handle situations when a case label is a special one ("case null", "case default", "default") but it's not a fallthrough one.
Move the methods that check if a statement can always execute its instructions from ControlFlowUtils to JavaControlFlowUtils in order to call them from PsiSwitchLabelStatementImpl
GitOrigin-RevId: 24c4aa3964be115b02fb499875fb97c89ea2ac08