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

@@ -35,7 +35,7 @@ export default {
   watch: {
     tooltipText() {
       $(this.$refs.tooltipTarget).tooltip('destroy');
-    }
+    },
   },
   computed: {
     tooltipClass() {
@@ -70,10 +70,7 @@ export default {
         :title="tooltipText"
         ref="tooltipTarget"
       />
-      <template
-        v-if="svg"
-        v-html="svg">
-      </template>
+      <svg v-if="svg" v-html="svg"></svg>
     </span>
   `,
 };