Introduce initial version of FIR Java type enhancement

Java type enhancement is performed by a special scope kind
Java FIR dump was added for multiplatform tests to look at enhancements
Overrides, J2K mapping, special cases does not work yet

Related to KT-29937

compiler/fir/cones/src/org/jetbrains/kotlin/fir/types/ConeTypes.kt

@@ -65,6 +65,10 @@ sealed class ConeKotlinType : ConeKotlinTypeProjection(), ConeTypedProjection, K
     abstract val nullability: ConeNullability
 }
 
+val ConeKotlinType.isNullable: Boolean get() = nullability != ConeNullability.NOT_NULL
+
+val ConeKotlinType.isMarkedNullable: Boolean get() = nullability == ConeNullability.NULLABLE
+
 class ConeKotlinErrorType(val reason: String) : ConeKotlinType() {
     override val typeArguments: Array<out ConeKotlinTypeProjection>
         get() = EMPTY_ARRAY