Evaluator: Support when expressions (EA-119639)

idea/testData/debugger/tinyApp/src/evaluate/singleBreakpoint/whenEvaluation.kt

@@ -0,0 +1,10 @@
+package whenEvaluation
+
+fun main(args: Array<String>) {
+    val a = "x"
+    //Breakpoint!
+    args.size
+}
+
+// EXPRESSION: when (a) { "a" -> "A"; "b" -> "B"; else -> "C" }
+// RESULT: "C": Ljava/lang/String;

idea/testData/debugger/tinyApp/src/evaluate/singleBreakpoint/whenEvaluation.out

@@ -0,0 +1,8 @@
+LineBreakpoint created at whenEvaluation.kt:6
+Run Java
+Connected to the target VM
+whenEvaluation.kt:6
+Compile bytecode for when (a) { "a" -> "A"; "b" -> "B"; else -> "C" }
+Disconnected from the target VM
+
+Process finished with exit code 0