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

spec/javascripts/vue_shared/components/user_avatar_image_spec.js

@@ -13,6 +13,7 @@ describe('User Avatar Image Component', function () {
         alt: 'mydisplayname',
         cssClasses: 'myextraavatarclass',
         tooltipText: 'tooltip text',
+        tooltipPlacement: 'bottom',
       };
       this.userAvatarImage = new UserAvatarImageComponent({