Mobile app should push user to update

[holmesworcester]

Once a user is sufficiently behind in releases (i.e. using a no-longer-supported release) the mobile app should warn them and encourage an upgrade.

This should link to the play store on Android or the App Store. It can say:

This version of Quiet is no longer supported and may not work correctly. For your community's safety, please update to the latest version.

On the backend, there should be some endpoint that lets us set the minimally supported version wherever we want, and we should incorporate updating this endpoint into our release process.

Design: https://www.figma.com/file/y8h6w8PYR9jyI3zjYHL9Cl/Mobile-%2B-desktop-%2B-prototypes?type=design&mode=design&t=x4qozDU6nbjuzo6h-0

[holmesworcester]