**Why?**
Currently the IDE loads a merge request based on only the
`source_branch` name. This means it loads MR's from
forks that have the same branch name (not good).

- This required updating the BE API to accept `source_project_id`

This isn't called from anywhere.

Partially addresses #47424.

This whitelists all existing offenses for the various CodeReuse cops, of
which most are triggered by the CodeReuse/ActiveRecord cop.

We had `item_project_ids` to help make slow queries on the dashboard faster, but
this isn't necessary any more - the queries are plenty fast, and we forbid
searching the dashboard without filters.

Deprecate corresponding dash versions created-by-me and assigned-to-me

And add support for additional query parameters:
- `author_id`: Returns merge requests created by the given user `id`
- `assignee_id`: Returns merge requests assigned to the given user `id`
- `scope`: Return merge requests for the given scope: `created-by-me`, `assigned-to-me` or `all`

The MergeRequestsFinder uses the milestone_title instead of the
milestone_id

counter

This is done by:
 - Extending the IssuableFinder adding the non_archived option to the params
 - Overriding the #filter_params in the MergeRequestsAction
 - Passing the non_archived param in the nav/_group.html.haml navbar
   partial from the groups/merge_requests.html.haml

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>