Fetch Reservation by Student and Menu

[macielti]

This pull request introduces a new feature to fetch a student's reservation by menu ID, along with related test cases and HTTP endpoints. Here are the most important changes:

New Functionality:

• Added fetch-student-reservation-by-menu function in src/rango_graalvm/controllers/reservation.clj to handle fetching reservations by student code and menu ID.
• Added fetch-student-reservation-by-menu function in src/rango_graalvm/db/postgresql/reservation.clj to query the database for reservations by student ID and menu ID.

HTTP Endpoints:

• Added a new API endpoint /api/reservation-by-student-and-menu in src/rango_graalvm/diplomat/http_server.clj to handle HTTP GET requests for fetching reservations by student and menu.
• Implemented the controller function for the new endpoint in src/rango_graalvm/diplomat/http_server/reservation.clj.

Testing:

• Added a new test function fetch-student-reservation-by-menu-test in test/integration/reservation_test.clj to test the new functionality.
• Added a helper function fetch-student-reservation-by-menu in test/integration/aux/http.clj to facilitate the testing process.
• Renamed test/integration/retract_reservation_test.clj to test/integration/reservation_test.clj to better reflect the expanded scope of the tests.