Horde 6 Release steps

One time importing from maintaina -

- Create a FRAMEWORK_6_0 branch from horde master
- Ensure the maintaina-com equivalent is rebased on master already
- PR content from the maintaina-com/FRAMEWORK_6_0 branch into the horde/FRAMEWORK_6_0 branch
- Make FRAMEWORK_6_0 the default branch
- add to packagist or change packagist URL from maintaina-com to horde
- Ensure the "horde" account and yunosh are among the owners/maintainers of the package

Make github actions work

WIP
- CI/PHPUnit, PHPStan
- PHPDOC
- satis

release from console (ignore the release github action for now)

TBD

setup packagist.org integration

TBD