Merge branch '21983-member-add_user-doesn-t-detect-existing-members-that-have-requested-access' into 'master'

Resolve "`Member.add_user`doesn't detect existing members that have requested access"

## What does this MR do?

This merge request handle the case when an access requester is added to a group or project (via the members page or the API).

In `Member.add_user`, if an access requester already exists, we simply accept their request (and set the `created_by`, `access_level` and `expires_at` attributes if given).

## Are there points in the code the reviewer needs to double check?

I've taken the opportunity to cleanup the whole `{Group,Project}Member.add_user*` methods since it was quite a mess.

## What are the relevant issue numbers?

Closes #21983

See merge request !6393

2 files changed, 2 insertions, 2 deletions

diff --git a/spec/finders/joined_groups_finder_spec.rb b/spec/finders/joined_groups_finder_spec.rb
index f90a8e007c8..29a47e005a6 100644
--- a/spec/finders/joined_groups_finder_spec.rb
+++ b/spec/finders/joined_groups_finder_spec.rb
@@ -43,7 +43,7 @@ describe JoinedGroupsFinder do
       context 'if profile visitor is in one of the private group projects' do
         before do
           project = create(:project, :private, group: private_group, name: 'B', path: 'B')
-          project.team.add_user(profile_visitor, Gitlab::Access::DEVELOPER)
+          project.add_user(profile_visitor, Gitlab::Access::DEVELOPER)
         end
 
         it 'shows group' do
diff --git a/spec/finders/projects_finder_spec.rb b/spec/finders/projects_finder_spec.rb
index 7a3a74335e8..13bda5f7c5a 100644
--- a/spec/finders/projects_finder_spec.rb
+++ b/spec/finders/projects_finder_spec.rb
@@ -38,7 +38,7 @@ describe ProjectsFinder do
 
       describe 'with private projects' do
         before do
-          private_project.team.add_user(user, Gitlab::Access::MASTER)
+          private_project.add_user(user, Gitlab::Access::MASTER)
         end
 
         it do