Minor code and style fixes (#5398)

* type fixes

* import fixes

* fix typos

* fix warning for private props that init in ctor only

* typing fixes

* typing fixes

* style cleanup

* fix test template

lib/core/directives/check-allowable-operation.directive.spec.ts

@@ -23,7 +23,8 @@ import { CoreModule } from '../core.module';
 import { TestBed } from '@angular/core/testing';
 
 @Component({
-    selector: 'adf-text-subject'
+    selector: 'adf-text-subject',
+    template: ''
 })
 class TestComponent implements NodeAllowableOperationSubject {
     disabled: boolean = false;

lib/core/directives/node-restore.directive.ts

@@ -34,7 +34,7 @@ export class RestoreMessageModel {
     selector: '[adf-restore]'
 })
 export class NodeRestoreDirective {
-    private restoreProcessStatus;
+    private readonly restoreProcessStatus;
 
     /** Array of deleted nodes to restore. */
     @Input('adf-restore')