Deep link to the MR list

Requirements

• When a user clicks on an entry in the MR panel, they should be navigated to the MR search results for the relevant MRs
• This URL varies based on whether the merge_request_dashboard feature is enabled. Ensure the links work regardless of the state of the feature flag.
  • When the feature flag is disabled, link to /-/merge_requests?params
  • When the feature flag is enabled, link to /-/merge_requests/search?params
• See &17924 (closed) for designs