Credit: [@Musisimaru](https://gitlab.com/Musisimaru) (originally
introduced in
[!229](https://gitlab.com/gitlab-org/gitlab-vscode-extension/-/merge_requests/229))

When we dispose commentController, all its therads will get disposed
automatically. We don't ever need to call dispose outside of the
GitLabCommentThread.

Added two new methods to the WrappedRepository: `reloadMr()` and
`getMr()`.

- `reloadMr()` will fetch additional information for the MR (for now
  it's the diff). It will also store this fetched information into a
  cache.
- `getMr()` expects that `reloadMr()` has been called in the past. It
  retrieves the MR information without making api calls.

This commit replaces the GitLabRepository(GitLabWorkspace) interface
with the Wrapped repository. The original objects `{ label, uri, error}`
were constructed by the issuable.ts.

We now use the WrappedRepository and the error state is signaled by a
new `containsGitLabProject` boolean flag. I.e. if the wrapped repository
doesn't contain GitLab project, there has been error during fetching it.

Also having access to the wrapped repository from within mr_item_model
is going to be important in the next commit because it allows us to
interact with the MR cache.

VS Code keeps the case. I.e. it  correctly replaces
even getWorkspaceFolders.

The only places where we didn't replace the string were when
we were using the VS Code API (vscode.workspace.workspaceFolders).

Excluding the position from overview notes was a small optimization.
Removing the condition simplifies the code at the cost of small
overhead (currently roughly 20 requests per hour).
After this change we'll always fetch the diff position.

If the comment changed on the server, but the extension still
shows the old version, we'll prevent the extension from overriding
the server's latest version. We'll warn the user that the
comment has changed since they last saw it.

This prevents confusion between GitLab project and VS Code workspace.
The current legacy naming that uses the name "project" to represent
VS Code workspace is diverging from an established naming and
confuses contributors.

The work "project" is used throughout the codebase for GitLab project
and it was causing confusion when two variables named 'project' meant
different things.

All logic related to creating vscode.CommentThread and
setting the correct properties has been extracted to one class.

This class will be responsible for resolving threads in the future.

The GitLabComment is going to be responsible for all comment-related
functionality like editing, deleting and reacting.

this limits the blast radius of existing GitLab issue
https://gitlab.com/gitlab-org/gitlab/-/issues/298827

This change starts fetching position for each discussion and then
it displays the discussions on diffs using the native VS Code API