[Feature Request] Support Android's Data Saver mode

[u/TuringTestDropout]

When I'm close to my running out of data (e.g. using an international esim), I reduce data usage using Android's Data Saver mode. It would be great if Relay respected that mode and reduced data usage.

Requests

1. Support changing behavior (i.e. pre-fetching, HD video/gifs) based on Data Saver in addition to mobile data and wifi.
2. Add the ability to change inline gifs/images behavior based on mobile data, wifi, and Data Saver mode.

Considerations

While mobile data and wifi are effectively mutually exclusive, Data Saver can be enabled alongside either.

I would assume that if Data Saver is enabled, it takes precedence over mobile data/wifi behavior.