Make Rvx builder Offline

[RabahPrime]

It is better to add an offline option because the apkmirror site works for me, but the api is not because I always use a VPN.

Windows 11

[Spacellary]

Let's watch the changes upstream, reis seems inclined to add this so we're good! :D

[inotia00]

https://github.com/inotia00/rvx-builder/issues/62