Add images upload feature for admin

At the admin dashboard, after the admin has logged in, should be able to upload images of new events. To elaborate the admin must be able to create, update, delete events. Events here only mean images related to upcoming workshops, seminars, and/or get togethers by TDH members. We are already using a mongodb collection.

- [ ] make a database for the images.
- [ ] add frontend to upload, delete or update
- [ ] connect this frontend to respective api calls
- [ ] students and visitors should be able to see these images on home page and/or the events page.