If an entry has been removed from the tree and later, during the same
session, a user is trying to add a new item with the same name/path we
should allow for that as long as the original entry is marked with
`deleted`.

**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.

This enables JavaScripts projects to have live previews straight in the
browser without requiring any local configuration. This uses the
CodeSandbox package `sandpack` to compile it all inside of an iframe.

This feature is off by default and can be toggled on in the admin
settings. Only projects with a `package.json` and a `main` key are
supported.

Updates happen in real-time with hot-reloading. We just watch for
changes to files and then send them to `sandpack` to allow it to reload
the iframe. The iframe includes a very simple navigation bar, the text
bar is `readonly` to stop users navigating away from the preview and
the back and forward buttons just pop/splice the navigation stack
which is tracked by a listener on `sandpack`

There is a button inside the iframe which allows the user to open the
projects inside of CodeSandbox. This button is only visible on
**public** projects. On private or internal projects this button
get hidden to protect private code being leaked into an external
public URL.

Closes #47268

Closes #44845

Closes #44845

This is to reduce the dependancy on the flash module which just modifies
the DOM, whereas this now correcly uses the vDOM

i18n

updated variable name
removed un-used prop

[ci skip]

added arrow key navigation in the dropdown
enter & click open the file
highlight occurrences of the searched text in the drppdown item
fixed some performance issues when rendering
limit the dropdown items to a maximum of 20 - this may change to more
depending on other performance changes

Closes #44841

pending tabs now get added into openfiles & just filtered correctly

Pending tabs are normal tabs that are opened from the right sidebar.
They are opened in diff mode and when changed to edit mode they get
closed
& the actual file gets opened.

Closes https://gitlab.com/gitlab-org/gitlab-ee/issues/4541

This also makes the IDE generally available

Closes #38360

spec fixes

[ci skip]

removed old store, helper & monaco loader
moved monaco loader into editor component because it is the only
component that requires monaco

[ci skip]