Add support for policy-managed storage

[jh-devv]

Hey!

It would be nice to add support for https://extensionworkshop.com/documentation/enterprise/enterprise-development/#how-to-add-policy so I could bundle stylus with my nix Firefox configuration, which depends on those policies.

[jh-devv]

This has been done at least on ublock

[tophf]

Settings/options might make sense. What else?

[jh-devv]

Settings/options might make sense. What else?

Maybe like:

• Settings for Stylus (e.g. Enable CSP patching)

• Downloading a list of styles and set their options

  That would be probably all?