Add Projects tab to the Profile page

After #89 is completed, we can add a "Projects" tab to the Profile page. The main purpose of this tab will be to show the submissions done by all the teams the user is a part of. Currently, this is not shown; instead, we can only see the user teams on the profile page.

### Tasks

- [ ] Investigate if submissions can be extracted from the existing data on the Profile page. Possible sources of this data are:
- Profile data stored in the Context in [context/auth.js ](context/auth.js)
- Data fetched on the profile page from the backend API `/profile/{username}`.
- Other APIs in the backend can be explored.
- [ ] If no such sources are found, or the sources are computationally expensive, file an issue on the [backend repository](https://github.com/COPS-IITBHU/hackalog-backend), mentioning this issue, for a new API to get the submission data of the user.
- [ ] Make a card for showing Projects. (If a component is already there, skip this step)
- [ ] Fetch the submission data from this source and show the data in cards.

After #89, start by reviewing context/auth.js and the profile page's /profile/{username} response to determine whether team submissions are already available; inspect other backend APIs if needed. Done means the Profile page has a Projects tab with cards showing submissions from all of the user's teams, or a linked backend-repository issue if a new API is required.

Written by the indexing model from the issue text.