Add UserManagement feature flag

[rdimitrov]

Summary

The following PR adds a feature flag for enabling User Management

Fixes: #3531

Change Type

Mark the type of change your PR introduces:

• Bug fix (resolves an issue without affecting existing features)
• Feature (adds new functionality without breaking changes)
• Breaking change (may impact existing functionalities or require documentation updates)
• Documentation (updates or additions to documentation)
• Refactoring or test improvements (no bug fixes or new functionality)

Testing

Outline how the changes were tested, including steps to reproduce and any relevant configurations.
Attach screenshots if helpful.

Review Checklist:

• Reviewed my own code for quality and clarity.
• Added comments to complex or tricky code sections.
• Updated any affected documentation.
• Included tests that validate the fix or feature.
• Checked that related changes are merged.

[coveralls]

coverage: 52.676% (-0.005%) from 52.681%
when pulling 7bcf307 on feature-flag
into 15af232 on main.

[coveralls]

coverage: 52.681% (+0.005%) from 52.676%
when pulling 46a8f1f on feature-flag
into eedd6ee on main.