IBX-11213: Updated translation modal footer hook and source language options

[mikadamczyk]

🎫 Issue	IBX-11213

Description:

This PR adjusts the translation modal in Admin UI to support the side‑by‑side (SxS) flow.
The SxS flow replaces the legacy "Create translation" action, so the modal footer needs to be extensible. The source language selector should not allow "No language" when SxS is enabled.

• Added a footer extension point in the translation modal to let translations-management inject the SxS button.
• Passed content_id (and location context) to the footer hook so the SxS action can build its route.
• Updated the translation add form options to disable the "No language" choice for the source selector when using the SxS flow.

This way, the modal remains in Admin UI, but its primary action can be replaced by SxS. The source language selector reflects only valid published languages for SxS.

For QA:

Documentation:

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud