refactor(nav): add underline-border variant

Author: xidedix

projects/coreui-angular/src/lib/nav/nav.component.scss

@@ -1,3 +1,10 @@
 :host .nav-link:focus {
   outline: 0;
 }
+
+// todo: temp fix for nav-underline-border
+:host.nav-underline-border {
+  column-gap: 0;
+}
+
+

projects/coreui-angular/src/lib/nav/nav.component.ts

@@ -14,9 +14,9 @@ export class NavComponent {
   @Input() layout?: 'fill' | 'justified';
   /**
    * Set the nav variant to tabs or pills.
-   * @type {'tabs' | 'pills' | 'underline'}
+   * @type 'tabs' | 'pills' | 'underline' | 'underline-border'
    */
-  @Input() variant?: '' | 'tabs' | 'pills' ;
+  @Input() variant?: '' | 'tabs' | 'pills' | 'underline' | 'underline-border';
 
   @HostBinding('class')
   get hostClasses(): any {