[FIR] Provide implementation of ExpectActualMatchingContext for FIR

^KT-58578

compiler/ir/ir.tree/tree-generator/src/org/jetbrains/kotlin/ir/generator/model/Transformations.kt

@@ -8,6 +8,7 @@ package org.jetbrains.kotlin.ir.generator.model
 import org.jetbrains.kotlin.ir.generator.config.*
 import org.jetbrains.kotlin.ir.generator.elementBaseType
 import org.jetbrains.kotlin.ir.generator.util.*
+import org.jetbrains.kotlin.utils.addToStdlib.UnsafeCastFunction
 import org.jetbrains.kotlin.utils.addToStdlib.castAll
 import org.jetbrains.kotlin.utils.addToStdlib.partitionIsInstance
 
@@ -82,6 +83,7 @@ fun config2model(config: Config): Model {
     return Model(elements, rootElement)
 }
 
+@OptIn(UnsafeCastFunction::class)
 private fun replaceElementRefs(config: Config, mapping: Map<ElementConfig, Element>): Element {
     val visited = mutableMapOf<TypeRef, TypeRef>()