meta.sr.ht: add API service

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

meta.sr.ht: use app, not app_dispatch, w/gunicorn

The latter has been removed now that instrumentation is built into
core.sr.ht.

meta.sr.ht: remove py3-prometheus-client dependency

This comes from py3-srht now

meta.sr.ht: move .billing location

sr.ht/meta.sr.ht: add -billing subpackage

meta.sr.ht/post-upgrade: run core.sr.ht migrations

meta.sr.ht: update to latest version

Update all dependency packages

Add zxcvbn to meta.sr.ht dependencies

Fix supervisor in meta.sr.ht init scripts

meta.sr.ht: normalize init scripts

Make local redis service optional

Add extra gunicorn args to *.init

Add webhooks init script to meta.sr.ht

Add -openrc, fix sources for meta.sr.ht

Fix more indentation issues

Update man.sr.ht.post-upgrade

Also moves alembic dependency to py3-srht

Update meta.sr.ht.post-upgrade

Update meta.sr.ht for prometheus support