This diff modifies all the github actions that produce assets to
publish on a release called rolling when we are not building a tag.
If everything goes as planned, we should be able to provide
people with automatically generated fresh binaries for testing.
While there, introduce caching for all builds to make them
as fast as possible. I suspect gomobile based builds will not
see any speed up but other builds most likely will.
See https://github.com/ooni/probe/issues/2249
Part of https://github.com/ooni/probe/issues/1753.
While there, introduce a rule by which, if the branch is named `fullbuild` we run all possible builds. It helps to test all the builds without creating a release branch. Because release branches are protected, they cannot be deleted easily. On the contrary, the `fullbuild` branch can easily be disposed of.
I am not 100% sure I was able to fix all the cases in which we
need higher permissions than the strict default.
At least, I tried.
It may be reasonable to make an interim release to check whether I
successfully fixed all the cases.
Ref issue: https://github.com/ooni/probe/issues/2154
