Filter endpoint

[niraymak]

Is your feature request related to a problem? Please describe.
Research a way to refactor the filter through projects endpoint.
https://github.com/DigitalExcellence/dex-backend/blob/develop/API/Controllers/ProjectController.cs#L160

Currently we have two very similar endpoints:
https://github.com/DigitalExcellence/dex-backend/blob/develop/API/Controllers/ProjectController.cs#L160
https://github.com/DigitalExcellence/dex-backend/blob/develop/API/Controllers/SearchController.cs#L66

Also there is a bug where the endpoint returns less projects than asked if there are institute private projects.

Describe the solution you'd like
Research and refactor the endpoint and flow.

Production URL

Additional context