Uses Suspense when loading projects

[simonbs]

This PR is made in response to this comment from @mpabarca, which raises a great point that Shape Docs isn't taking advantage of React's Suspense or other built-in features of Next.js for managing loading states.

While this PR doesn't fully address all the points made in the comment, it addresses part of it. Specifically, this PR removes our /api/user/projects endpoint, which we previously used alongside SWR to refresh the user's list of projects.

Instead, we now fetch the projects directly from our IProjectDataSource in the ProjectList component. When doing so, we utilize Suspense with a fallback that includes the following logic:

1. Display projects retrieved from our server-side cache, specifically from Redis.
2. If there are no projects cached server-side, display a loading state.

I have not previously worked with Suspense and Next.js' features for managing loading states, so I would greatly appreciate feedback on the approach presented in this PR to learn how to do it best 🙏

[simonbs]

It was a challenge to ensure that the logic was properly split between the server-side and client-side, specifically making sure that anything using useContext(...) runs on the client-side, while the component fetching the data from our IProjectDataSource (DataFetchingProjectList, in our case) resides on the server-side. That's why a relatively large number of files are changed in this PR.