refactor(icons): replace FontAwesome with Tabler Icons

Drop the three @fortawesome/* packages (v5, with a stagnant Vue 2
binding) in favor of @tabler/icons-webfont. The old <awe-icon>
wrapper is replaced by <vaquant-icon>, named after the project so
future icon-library swaps don't require another rename.

src/components/TransactionCreate.vue

@@ -220,7 +220,7 @@
       :margin="true"
       :button-style="backgroundColor"
     >
-      <awe-icon icon="check" />
+      <vaquant-icon icon="check" />
     </fab-button>
   </div>
 </template>