Change links to buttons

- more semantically accurate, will expose these as buttons to assistive technologies
- note: while having block-level elements like `<div>` inside a `<button>` is an html validation error, it does not affect functionality as long as there's no more structure inside it

src/popup/vault/password-history.component.html

@@ -20,10 +20,10 @@
                     </div>
                 </div>
                 <div class="action-buttons">
-                    <a class="row-btn" href="#" appStopClick appA11yTitle="{{'copyPassword' | i18n}}"
+                    <button type="button" class="row-btn" appStopClick appA11yTitle="{{'copyPassword' | i18n}}"
                         (click)="copy(h.password)">
                         <i class="fa fa-lg fa-clone" aria-hidden="true"></i>
-                    </a>
+                    </button>
                 </div>
             </div>
         </div>