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/pipelines/pipeline_url_spec.js

@@ -60,7 +60,7 @@ describe('Pipeline Url Component', () => {
     expect(
       component.$el.querySelector('.js-pipeline-url-user').getAttribute('href'),
     ).toEqual(mockData.pipeline.user.web_url);
-    expect(image.getAttribute('title')).toEqual(mockData.pipeline.user.name);
+    expect(image.getAttribute('data-original-title')).toEqual(mockData.pipeline.user.name);
     expect(image.getAttribute('src')).toEqual(mockData.pipeline.user.avatar_url);
   });