Fix the user's requests page
    
    We used to include the projects in which an user had opened at one point
    a pull-request in, this lead to a lot of false positive.
    Now we're being strickter about when retrieving the list of projects
    and adding the pull-requests that the used opened in a second step.
    
    So the logic is something like:
    - Get all the projects the user is involved in (direct access or via a
      group)
    - Get all the PRs in these projects + all the PRs opened by that user
    - Group them all into one final query that is then ordered/filtered as
      desired
    
    Fixes https://pagure.io/pagure/issue/2930
    
    Signed-off-by: Pierre-Yves Chibon <pingou@pingoured.fr>