MAB-746: User List Page- Add filter per country

[Joselgc1]

Description

The user list page in the back-office only had filters for name/username search and role. Added a Country dropdown filter alongside the existing role filter in the advanced filters section that reuses the country choices already being fetched from the reference data API for the table's Country column display.

Useful links

• https://www.notion.so/User-List-Page-Add-filter-per-country-319d463fd8c480ec9ad3dd0d4cd73022?source=copy_link

Type of change

• New feature (non-breaking change which adds functionality)
• Improvement (refactor or addition to existing functionality)

Checklist:

( * == Mandatory )

• * I have set myself as assignee of the pull request
• * My code follows the style guidelines of this project
• * Linting does not generate new warnings
• * I have performed a self-review of my own code
• * I have put the ticket for review, adding the oort-frontend team to the list of reviewers
• * I have commented my code, particularly in hard-to-understand areas
• * I have put JSDoc comment in all required places
• * My changes generate no new warnings
• * I have included screenshots describing my changes if relevant
• * I have selected labels in the Pull Request, according to the changes with code brings
• I have made corresponding changes to the documentation ( if required )
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules