reproducible Archlinux: layout plan how to switch to sql based html

* maintenance job:

** check for archlinux schroot sessions which should not be there and delete them. complain if that fails.

* html

** disable html + builder jobs

** then rename all diffoscope html files to diffoscope_results.html

** then rename all good pkg html files to index.html

** if ! -f pkg.state || ! -f index.html... recreate

** create index.html for all ftbr pkgs

** create index.html for all other pkgs

** include link to debian note if it exists

** create page for untested packages?

* use db

** problem: we currently have more (detailed) stati in archlinux

** extend scheduler.sh:

*** check/make sure that packages which are newer in trunk than repo are only scheduled once

** make build.sh

*** write db

**** write temp script to populate db with known date: pkg.state, pkg.build_date. stop builders and html job when running this

**** save state details on fs until we know better / the answer to the problem above

*** do not share /var/log/jenkins/reproducible-race-conditions.log with debian

*** make build respect pacman exit code

** create new job to recreate all pkg pages

** call pkg html function after each build

** html

*** disable all current html creation

*** leave all files, delete them (much) later

*** recreate them newly as index.html

**** create new job to recreate all pkg pages

**** call pkg html function after each build

*** create index pages

*** create new archlinux.html - keep the old one til this works

** cleanup now useless code from scheduler

** create json