feat: enable multiple technical user for offers

[Phil91]

Description

Remove the limitation to only have one technical user per offer

Why

To create multiple technical users for an offer

Issue

Refs: #1136

Checklist

• I have followed the contributing guidelines
• I have performed IP checks for added or updated 3rd party libraries
• I have created and linked IP issues or requested their creation by a committer
• I have performed a self-review of my own code
• I have successfully tested my changes locally
• I have added tests that prove my changes work
• I have checked that new and existing tests pass locally with my changes
• I have commented my code, particularly in hard-to-understand areas

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
4 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[Phil91]

@typecastcloud no the frontend didn't adjust the logic yet, but we could already merge the backend since it only enables the creation without changing any request nor response type to the frontend

[typecastcloud]

I have reviewed, built and tested the code. Approval from me.

Tech user/service account naming conventions still cause some confusion but that will take some time to streamline I guess.

[Phil91]

I have reviewed, built and tested the code. Approval from me.

Tech user/service account naming conventions still cause some confusion but that will take some time to streamline I guess.

Would maybe make sense if you could add an issue for that? than we could continue the discussion on what's needed there