fix(sidebar-nav): @angular/router has no exported member QueryParamsHandling

see:
- angular/angular#30925
- angular/angular#30816
- https://stackoverflow.com/questions/58890574/path-node-modules-angular-router-router-has-no-exported-member-queryparamsha

Author: xidedix

CHANGELOG.md

@@ -1,5 +1,10 @@
 ### [@coreui/angular](https://coreui.io/) changelog
 
+##### `v2.7.x`
+- fix(sidebar-nav): @angular/router has no exported member QueryParamsHandling, see: 
+    - https://github.com/angular/angular/issues/30925
+    - https://github.com/angular/angular/issues/30816
+
 ##### `v2.7.0`
 - chore: upgrade to Angular 9 - see also: 
     - `https://next.angular.io/guide/updating-to-version-9`

projects/coreui/angular/src/lib/sidebar/app-sidebar-nav.ts

@@ -1,5 +1,3 @@
-import {QueryParamsHandling} from '@angular/router';
-
 export interface INavAttributes {
   [propName: string]: any;
 }
@@ -23,7 +21,7 @@ export interface INavLabel {
 export interface INavLinkProps {
   queryParams?: {[k: string]: any};
   fragment?: string;
-  queryParamsHandling?: QueryParamsHandling;
+  queryParamsHandling?: 'merge' | 'preserve' | '';
   preserveFragment?: boolean;
   skipLocationChange?: boolean;
   replaceUrl?: boolean;