Majors and Courses Details endpoints

Added endpoints for /majors and /courses

New endpoints:

GET /school-years: return an Array of available school years
GET /majors/:schoolYear: Accepts a school year as a URL parameter and returns a list of major names available for that year, facilitating a user-friendly way to explore academic options.
POST /majors: Allows clients to post a JSON body with optional schoolYear and required majorName to fetch detailed information about a specific major. If schoolYear is omitted, the most recent year is used by default.
GET /courses/:schoolYear: Similar to the majors endpoint, but for courses, returning a list of courses available in the specified school year.
POST /courses: Clients can submit a JSON body with optional schoolYear and required courseId to get detailed information about a specific course, defaulting to the most recent school year if none is specified.

added tests cover scenarios such as valid and invalid inputs, the absence of optional parameters, and checks for the correct response structure and HTTP status codes for /courses and /majors endpoints