Introduce experimental FIR compiler #KT-31265 Fixed

This commit also includes several FIR2IR fixes which helps FIR compiler
to produce normal results

compiler/testData/cli/jvm/firHello.kt

@@ -0,0 +1,12 @@
+fun box(): String = "OK"
+
+
+class E(s: String) : Exception(s) {
+
+}
+
+fun main(args: Array<String>) {
+    if (box() == "OK") {
+        throw E("Hello")
+    }
+}