[Feature]: Add a filesystem backend

[J-Cake]

Is there an existing issue for this?

• [X] I have searched the existing issues

Summary

The ability to read data from the local filesystem would be wonderful. I'm hoping for the following features:

• List directories recursively
• Copy/Move files recursively
• Delete recursively
• Read/Write file contents in a streaming fashion
• Inspect file properties like size, modified etc
• Subscribe to filesystem changes

Why should this be worked on?

As an example, I'm working on a dashboard for our company's website. We don't have huge needs, so a static site is fine, but I'd like to be able to parse the filesystem to find translated pages, get last-modified dates automatically, resolve merge conflicts etc. Since we use a static file server, the source is not stored in a database anywhere. Without implementing my own API, this would be quite cumbersome.

[J-Cake]

As a nice-to-have feature would be the ability to spawn executables with this backend. If the security implications of this are of concern (which they should be), then perhaps this should be feature-gated, or come with a warning.