Add Custom Proxy Headers to mobile app

[mattiaginoble]

Is your feature request related to a problem? Please describe. If you have placed your self-hosted Cloudreve application behind a forward authentication layer such as Cloudflare Zero Trust (or perhaps a self-hosted Authentik or Authelia), you will not be able to run the mobile application.

Describe the solution you'd like Use service access tokens. This way, we can ensure that our mobile app continues to communicate with our API by bypassing the zero trust access level with a special secret that we can instruct Cloudreve to use in its requests.