Switch issues and CI to GitHub

[Lao Shaw]

+1

Yes let's move to github.

github is used by so many open source projects and it becomes the de
facto git repo platform for many, what makes openwrt so special to the
point that github is not good enough and your idea will do better(for
long term with reliability and easy to maintain)? what exactly is that
and why all those OSS projects are fine with it.

Move the CI and repos  and issues and even discussions to github so
the resource-limited core developers can focus on evolving openwrt
itself, instead of spending cycles on its infrastructure.

Shaw