Consolidate user avatar Vue logic

Creates 3 vue components:

1. user-avatar-link
2. user-avatar-image
3. user-avatar-svg

and implements them in several places.

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/31017

• Port to EE
• Test each implementation manually

EE Compatible Branch: https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/1699

app/assets/javascripts/vue_shared/components/user_avatar/user_avatar_link.vue

@@ -54,7 +54,7 @@ export default {
       :css-classes="imgCssClasses"
       :size="imgSize"
       :tooltip-text="tooltipText"
-      tooltip-placement="tooltipPlacement"
+      :tooltip-placement="tooltipPlacement"
     />
   </a>
 </template>