[FIR] Add @Supress("unused") to debug and plugin-related declarations

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/calls/tower/TowerGroup.kt

@@ -45,7 +45,7 @@ sealed class TowerGroupKind(val index: Byte) : Comparable<TowerGroupKind> {
 
     class Local(depth: Int) : WithDepth(6, depth)
 
-    class ImplicitOrNonLocal(depth: Int, val kindForDebugSake: String) : WithDepth(7, depth)
+    class ImplicitOrNonLocal(depth: Int, @Suppress("unused") val kindForDebugSake: String) : WithDepth(7, depth)
 
     class ContextReceiverGroup(depth: Int) : WithDepth(8, depth)
 

compiler/fir/tree/src/org/jetbrains/kotlin/fir/extensions/predicate/PredicateVisitor.kt

@@ -41,5 +41,9 @@ abstract class PredicateVisitor<P : AbstractPredicate<P>, R, D> {
     }
 }
 
+// It can be used externally by plugins
+@Suppress("unused")
 typealias DeclarationPredicateVisitor<R, D> = PredicateVisitor<DeclarationPredicate, R, D>
+// It can be used externally by plugins
+@Suppress("unused")
 typealias LookupPredicateVisitor<R, D> = PredicateVisitor<LookupPredicate, R, D>

compiler/fir/tree/tree-generator/src/org/jetbrains/kotlin/fir/tree/generator/util/HierachyGraphGenerator.kt

@@ -9,6 +9,8 @@ import org.jetbrains.kotlin.fir.tree.generator.context.AbstractFirTreeBuilder
 import org.jetbrains.kotlin.fir.tree.generator.model.Implementation
 import java.io.File
 
+// It's used to generate a graph in dot format (it's useful for debugging)
+@Suppress("unused")
 fun printHierarchyGraph(builder: AbstractFirTreeBuilder) {
     fun Implementation.Kind.toColor(): String = when (this) {
         Implementation.Kind.Interface -> "green"