Create classroom management page

[Max-Harold]

• Create a blank page for the classroom management at /classroom/manage
• Add the nav bar and the name of the classroom to the page
• Create the necessary components
  • Create a component ClassroomSidebar that has the buttons labeled "Details, Students, Assignments," and "Grades" that the teacher will click on to change the main content of the page.
  • Create a CalendarInput component that modifies the <input type="date" /> field
  • Create a TextArea component for the course description.
  • Create a SelectDropdown component for the visibility dropdown input
  • Create a Popup component that can somehow darken its entire parent and be displayed at the center of its parent
• Create an api endpoint /api/classroom/testcase/<testcase_id> that deletes a testcase
  • Connect this endpoint to the frontend
• Make the classroom management page only show if the user has the proper role to manage the classroom