Test - GetBrowseAdsPage_WhenRequestIsInvalid_ShouldReturnUnsuccessfulResponse

Tests:
- GetBrowseAdsPage_WhenPageNumberIsLargerThanAvailable_ShouldReturnLastPage
- GetBrowseAdsPage_WhenRequestIsValid_ShouldReturnCorrectNumberOfAds
- GetBrowseAdsPage_WhenRequestIsValid_ShouldReturnCorrectTotalPages
- GetBrowseAdsPage_WhenRequestIsValid_ShouldReturnCorrectAds

Tests:
- GetAdDetails_WhenAdDoesntExist_ShouldReturnNull
- GetAdDetails_WhenUserIsOwner_ShouldReturnCorrectUserRelationship
- GetAdDetails_WhenUserIsAcceptedStudent_ShouldReturnCorrectUserRelationship
- GetAdDetails_WhenUserIsPendingStudent_ShouldReturnCorrectUserRelationship
- GetAdDetails_WhenUserIsHasNoRelationshipToAd_ShouldReturnCorrectUserRelationship
- GetAdDetails_WhenAdExists_ShouldReturnCorrectAdDetails

Also added 1 helper method - SetupMockGetAdById

- GetUsersSchedule_WhenUserHasNoAds_ShouldReturnEmptyTutorsSchedule
- GetUsersSchedule_WhenUserHasNoScheduleItemRequests_ShouldReturnEmptyStudentsSchedule
- GetUsersSchedule_WhenUserHasAdsWithScheduleItems_ShouldReturnCorrectTutorsSchedule
- GetUsersSchedule_WhenUserHasScheduleItemRequests_ShouldReturnCorrectStudentsSchedule
- GetUsersSchedule_WhenNoStudentIsAccepted_ShouldReturnNullAcceptedStudentsName
- GetUsersSchedule_WhenAStudentIsAccepted_ShouldReturnStudentsName
- GetUsersSchedule_WhenRequestIsAccepted_ShouldReturnCorrectStatus
- GetUsersSchedule_WhenRequestIsPending_ShouldReturnCorrectStatus

Also added and modified some helper methods.

- Change in method name
- Fixed incorrect assertion
- Spacing adjustments
- Added and renamed some actual and expected variables