Reshaping repo

The repo is designed for use with an existing builds.sr.ht service.
Besides lacking that, I am more interested in a containerized workflow
powered by a Makefile. Package source code will live in `pkgsrc/`,
packages will be built into `pkg/`, and packaging keys will be
generated into `keys/`.

Alos trimmed the packages down to what I will build.

Fix various user creation bugs and inconsistencies

- ensure that all users are added to their corresponding groups
- replace listssrht user with lists
- ensure that the git user creates its homedir
- ensure that adduser args are in same order across all apks

Fix git.sr.ht user creation

Add git.sr.ht package