Use vue files for vue components.

What does this MR do?

Part 5 of moving into vue files:

Uses vue files for environments Removes environment app initialisation from global namespace

Does this MR meet the acceptance criteria?

• Tests
  • All builds are passing
• Conform by the merge request performance guides
• Conform by the style guides
• Branch has no merge conflicts with master (if it does - rebase it please)
• Squashed related commits together

What are the relevant issue numbers?

https://gitlab.com/gitlab-org/gitlab-ce/issues/31156