[FR] Individual directories for each page

### Description

Currently, there is no way to transfer or save an individual page. This makes it challenging to keep a page constantly updated on all devices. What I suggest is to make each page have its own directory. This would allow git repositories to be made to allow hosting and easier save management for individual pages. With this, you could even make pages and documents their own individual files, and it could be a readable format like a modified *markdown* or *HTML*.

### Impact

Everyone really. This would be a general quality of life allowing easier access for personal use and for teams.

### Additional Context

- Page Directory
- Info.apfy (Maybe a file to store basic info about the page?)
- document1.apfy (maybe an AppFlowy file format)
- document2.apfy