Switch kotlin version to 1.8

with appropriate fixes in testdata, tests and other
places.

compiler/testData/diagnostics/tests/controlFlowAnalysis/UninitializedEnumCompanionVals.kt

@@ -1,7 +1,7 @@
 // SKIP_TXT
 
 enum class A(val z: Any) {
-    Y(<!UNINITIALIZED_ENUM_COMPANION_WARNING, UNINITIALIZED_VARIABLE!>x<!>);
+    Y(<!UNINITIALIZED_ENUM_COMPANION, UNINITIALIZED_VARIABLE!>x<!>);
 
     companion object {
         val x = A.Y.ordinal
@@ -9,7 +9,7 @@ enum class A(val z: Any) {
 }
 
 enum class B(val z: Any) {
-    Y(<!UNINITIALIZED_ENUM_COMPANION_WARNING!>B<!>.x);
+    Y(<!UNINITIALIZED_ENUM_COMPANION!>B<!>.x);
 
     companion object {
         val x = B.Y.ordinal