Setup Vue application for organization front page

What does this MR do and why?

Related to #421448 (closed)
Designs: &11187

The grouptenant scale team is starting to build out an Organization MVC. For more information about what an "Organization" will be see https://docs.gitlab.com/ee/user/organization/

This MR continues starts building the front page by setting up the Vue application and adding the avatar. More progress on the front page to come in &11187

UX notes

• The Organizations::Organization model does not yet support a description so we will be adding that in #422078 (closed)
• Subscriptions will not be part of the MVC so I have left it out of the avatar. Confirmed with PM &11187 (comment 1514168095)

Screenshots or screen recordings

Desktop	Mobile

How to set up and validate locally

1. Open Rails console
   • bin/rails console
2. Enable the feature flag
   • Feature.enable(:ui_for_organizations)
3. Create an organization
   • FactoryBot.create(:organization, name: 'GitLab', path: 'gitlab')
4. Navigate to /-/organizations/gitlab/groups_and_projects

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.