Add "new publication" button.

frontend/src/app/pages/my-publications/my-publications.component.html

@@ -1,4 +1,12 @@
 <h1>Your publications</h1>
+
+<a [routerLink]="['/publications/new']"
+    class="new-publication"
+    matTooltip="Add a new publication"
+    matTooltipPosition="left">
+    +
+</a>
+
 @if ((isLoading$ | async) === true) {
     <h2>Publication loading...</h2>
     <mat-spinner></mat-spinner>