FIR IDE: add action to override/implement missing members

This commit adds the following actions:

- quickfix to implement missing members
- quickfix to implement missing members as constructor parameters
- action to implement members (Code - Generate - Implement)
- action to override members (Code - Generate - Override)

The current implementation is still missing some pieces, which will be
addressed in future changes.

- fully qualified names are not shorten
- some Kotlin types are not rendered correctly

compiler/fir/tree/src/org/jetbrains/kotlin/fir/declarations/FirDeclarationUtil.kt

@@ -57,6 +57,12 @@ inline val FirRegularClass.isFun get() = status.isFun
 inline val FirMemberDeclaration.modality get() = status.modality
 inline val FirMemberDeclaration.isAbstract get() = status.modality == Modality.ABSTRACT
 inline val FirMemberDeclaration.isOpen get() = status.modality == Modality.OPEN
+inline val FirMemberDeclaration.isFinal: Boolean
+    get() {
+        // member with unspecified modality is final
+        val modality = status.modality ?: return true
+        return modality == Modality.FINAL
+    }
 
 inline val FirMemberDeclaration.visibility: Visibility get() = status.visibility
 inline val FirMemberDeclaration.effectiveVisibility: EffectiveVisibility