This is necessary so that specs do not leave behind
state that's accidentally picked up by other specs 

https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/31694#note_202415722

Also cleans up spec by:
- Add missing `afterEach ... $destroy`
- Add missing `done` call when `$nextTick` was used

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/59802

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/51737

The batch comments module now gets dynamically registered only in EE.

Closes https://gitlab.com/gitlab-org/gitlab-ee/issues/10008

Fixes some diff files not rendering when the renderIt
property is updated.
Previously it was using a local copy of renderIt which meant
Vue wouldn't update it when the files renderIt property was updates

- replaced file.too_large
- replaced file.text
- replaced file.collapsed

Renders mode changed and renamed file merge request diff
viewers on the frontend.

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/52607

This caused many pain points when working with it.
Part of the data was camel cased the other snake case.
Other parts where snake case & then getting converted in components,
this conversion has the potential for leaking memory.

This changes that & makes it consistent with what it returned from the
API, snake case.

This fixes files that are collapsed by default not expanding
when the expand all button is clicked.

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/53866