[FIR] Add pretty toString to CallKind

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/calls/CallKind.kt

@@ -74,6 +74,10 @@ sealed class CallKind(vararg resolutionSequence: ResolutionStage) {
     internal class CustomForIde(vararg resolutionSequence: ResolutionStage) : CallKind(*resolutionSequence)
 
     val resolutionSequence: List<ResolutionStage> = resolutionSequence.toList()
+
+    final override fun toString(): String {
+        return this::class.simpleName ?: super.toString()
+    }
 }
 
 class ResolutionSequenceBuilder(
@@ -111,4 +115,4 @@ class ResolutionSequenceBuilder(
 
 fun buildCallKindWithCustomResolutionSequence(init: ResolutionSequenceBuilder.() -> Unit): CallKind {
     return ResolutionSequenceBuilder().apply(init).build()
-}
+}