`items propagation` and `groups propagation` step by step transactions

[GeoffreyHuck]

For now in the worst case, the items propagation took ~6s. Since the process acquires a lot of write locks, it makes other select queries for other services wait for this amount of time. This doesn't fully solve the waiting problem though. It just makes the wait faster because the transactions are now smaller. The code is a bit weird because we still have two cases where the group propagation have to be executed inside a bigger transaction:

• The CreateRelation function, used in the groupAddChild and the accessTokenCreate and refreshToken (for the badges) services.
• The DeleteRelation function, used only in the groupRemoveChild service. Once those cases are removed, the code can be simplified, and look more like the other propagations.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 100.00%. Comparing base (1393a31) to head (073cb2a). Report is 2 commits behind head on master.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #1064 +/- ## ========================================= Coverage 100.00% 100.00% ========================================= Files 236 236 Lines 14254 14260 +6 ========================================= + Hits 14254 14260 +6 ```

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