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_image.js

@@ -43,7 +43,7 @@ export default {
     },
   },
   template: `
-    <span>
+    <span class="avatar-image-container">
       <img
         v-if="!svg"
         :class="imgCss"
@@ -57,8 +57,7 @@ export default {
       <span
         v-if="svg"
         v-html="svg">
-      </span>
-    </span>
+      </span></span>
   `,
 };