if any of the 3 agreements for creating campaign are not checked -> throw a HttpException with status 405

http error code is now 400 in validation for all 3 agreements  in create method

changed the error from HttpException to BadRequestException for the agreements validation in create method in campaign-application.service.ts

created findAll functionality in campaign-application.service and add testing for the method

new the mocked campaign-applications in the tests have the right schema(schema of the campaign-application)

This reverts commit cb14fdf.

remove unused providers in campaign-application.spec.ts
add validation if user is admin in findAll method in campaign-application.controller.ts
add tests for findAll method