sxmo/*: drop, upstreamed to Alpine

These packages have been upstreamed to alpine (https://gitlab.alpinelinux.org/alpine/aports/-/merge_requests/20927). They can be dropped from the master branch as per @minlexx on irc.

Related: issue #1068

After the next alpine release, we will add these packages to community/ on alpine. As such, the next pmOS release must have these packages on the version branch.