Code completion updates for enhanced switches (IDEA-202340)

- Support inside switch expression
- Support rule-based labels
- Support break inside expression
- Suggest 'switch' keyword in expressions
- Insert ':' or '->' depending on the switch type

java/java-tests/testData/codeInsight/completion/normal/SwitchExpressionStart.java

@@ -0,0 +1,5 @@
+public class ConstConfig {
+    int test(int x) {
+        return sw<caret>
+    }
+}