[FE] Type-safety refactoring: extract main logic of areCompatibleCallables into two functions

Review: https://jetbrains.team/p/kt/reviews/11039/timeline

Extract main logic of `areCompatibleCallables` into two functions:
`areStrongIncompatibleCallables` and `areWeakIncompatibleCallables`.

The main point is that `areStrongIncompatibleCallables` &
`areWeakIncompatibleCallables` have very specific return types.

This commit doesn't change any logic. The commit makes the API more
type-safe ensuring that bugs like in previous commit (KT-60902) won't
happen again

compiler/frontend/src/org/jetbrains/kotlin/resolve/checkers/ExpectedActualDeclarationChecker.kt

@@ -505,11 +505,10 @@ class ExpectedActualDeclarationChecker(
 
     companion object {
         fun Map<out ExpectActualCompatibility<MemberDescriptor>, Collection<MemberDescriptor>>.allStrongIncompatibilities(): Boolean =
-            this.keys.all { it is Incompatible && it.kind == IncompatibilityKind.STRONG }
+            this.keys.all { it is Incompatible.StrongIncompatible }
 
         internal fun ExpectActualCompatibility<MemberDescriptor>.isCompatibleOrWeakCompatible() =
-            this is Compatible ||
-                    this is Incompatible && kind == IncompatibilityKind.WEAK
+            this is Compatible || this is Incompatible.WeakIncompatible
     }
 }