Allow enabling mobile hotspot with data saver on

[Lppsoeht]

Low priority, but there are certain circumstances where the user needs to enable the hotspot(some apps for example) but he still wants apps to treat the networking as data saver is still on.
Enabling the hotspot has nothing to do with using lots of cellular data.
It's an inconvenience having to disable and reenable data saver on and on.

[neelchauhan]

I have a PR for this: GrapheneOS/platform_packages_apps_Settings#308

Since I cannot test it in the emulator I'll need to get a spare Pixel to test.

[thestinger]

This seems fine. It's strange that it disables it.

[neelchauhan]

The issue wasn't the emulator, but instead I removed a line of code which was critical. I reinstated the code.

Please review my GrapheneOS/platform_packages_apps_Settings#308 when you can.

[neelchauhan]

The good news is this PR works, but the bad news is that there are still UI bugs:

• The statusbar gets stuck on "data saver on" even when this option is on

I'll add another PR for the statusbar.

Video: https://youtu.be/NlHA_toPIc4