Convert Admin "Users" view from HAML to Vue MVP implementation
### Proposal
Migrate the admin/users **table** over to Vue using a serializer https://gitlab.com/gitlab-org/gitlab/-/issues/285103 to pass the data from HAML.
See original implementation discussion https://gitlab.com/groups/gitlab-org/-/epics/4683#note_444163859.
### FAQs
#### Why only convert the table for the MVP?
- It's the **m**inimum iteration we need to unblock several ~feature issues and deliver user value:
- ~"group::access" [making columns sortable](https://gitlab.com/gitlab-org/gitlab/-/issues/238181)
- ~"group::access" [adding filter categories](https://gitlab.com/gitlab-org/gitlab/-/issues/238183)
- ~"group::compliance" [show total group count for users](https://gitlab.com/gitlab-org/gitlab/-/issues/276215)
#### Why not consume the data from a API?
- We're planning on moving to GraphQL https://gitlab.com/gitlab-org/gitlab/-/issues/290276
- The admin users API doesn't have all the required fields https://gitlab.com/groups/gitlab-org/-/epics/4683#note_438427243.
- [Add `blocked_pending_approval` to users API](https://gitlab.com/gitlab-org/gitlab/-/issues/276195)
- [Add `deactivated` to admin users API
](https://gitlab.com/gitlab-org/gitlab/-/issues/276196)
- Creating a users store will add extra complexity to the first iteration and will be done as a follow-up.
#### What's next after we converted the table to Vue?
- Migrate pagination to Vue https://gitlab.com/gitlab-org/gitlab/-/issues/285105
- Migrate to GraphQL https://gitlab.com/gitlab-org/gitlab/-/issues/290276
- Create admin users store (Note: This may not be required with GraphQL)
- Migrate the admin actions to the store
- edit
- block
- deactivate
- delete
- delete-with-contributions
- Use the URL filter params to fetch the data from the API
See the full implementation with next-ups discussed in https://gitlab.com/groups/gitlab-org/-/epics/4683#note_435131368.
epic