Add enumeration support. (#128)

* Add enumeration support.

* Enum classes lowering.

* merge fix

* merge fix

* used arrayOf from irModule

* changed lowering quant from body to file

* refactoring

* review fixes

* lowering for GET_OBJECT in enums

* enabled tests

* added tests

* moved tests to separate dir

* renamed test files

* moved phase up

* review fixes

* reformat

backend.native/tests/codegen/enum/vCallWithEntryClass.kt

@@ -0,0 +1,15 @@
+enum class Zzz {
+    Z1 {
+        override fun f() = "z1"
+    },
+
+    Z2 {
+        override fun f() = "z2"
+    };
+
+    open fun f() = ""
+}
+
+fun main(args: Array<String>) {
+    println(Zzz.Z1.f() + Zzz.Z2.f())
+}