Important to get file data for any file that has no content set yet: we
need this information in order to build a previe for changed/staged
files if they were not yet opened in the editor

i18n linting for .vue files under the
app/assets/javascripts/ide directory

- On CMD+S when editor is focused
- On editor blur
- When file is created in tree
- When file is removed in tree
- When file is renamed in tree

This reverts commit e8c1c930c3bc7c159463ed3bed8765db01b40328.

Instead of ContentViewer attempts to compute file type and render
appropriate viewer type, compute it on the parent RepoEditor having all
file-related information at its disposal and pass it down to
ContentViewer as a prop

Upgrades prettier to 1.15.3
Runs `yarn prettier-save-all` against the codebase
Most changes are due to https://github.com/prettier/prettier/pull/5519

**Why?**
- This is needed for the Web Terminal feature.
  https://gitlab.com/gitlab-org/gitlab-ee/issues/5426

**Notes:**
- Introduces a `pane` Vuex module.
- Some views should not be kept alive (i.e. job details).
  This is why a `keepAlive` flag was introduced for views.

Closes #47947

Closes #47763

Closes #46392

i18n

fixed review mode not being editable

added computed prop for showing loading indicator

only make diff mode editable in review mode

#44846

added spec to check for `head` file

fixed files getting into an opened & active state when it shouldnt

fixed `key` not being set to correct value