Continuous integration fixes

[amulet1]

Redesign ci.yml to work again:

• Replace unsupported ubuntu-20.04 with ubuntu-22.04
• Drop support for PHP 7.4 and 8.0
• Add support for PHP 8.1, 8.2, 8.3, 8.4
• Remove unused ssh keys
• Allow horde/horde-installer-plugin
• Other improvements

The redesigned ci.yml should probably be used in other Horde apps.

Add psr/http-factory to composer.json

Note, to work properly under PHP 8.2+ it also requires horde/Test#8 to be merged.

[amulet1]

@TDannhauer Please review/merge.

[amulet1]

With the latest commit phpunit can be called without --bootstrap test/bootstrap.php parameter, and it will work even if vendor folder is outside.

@TDannhauer Please merge.

[TDannhauer]

I think I'm not the best reviewer here. lets discuss it with @ralflang next week.

[amulet1]

OK. But... note, the current ci.yml does not work at all as it refers to no longer supported Ubuntu versions. Even if version is changed, the existing code causes issues in PHP 8.2+ (see horde/Test#8).

So, the worst that can happen is that it still does not work (but I tested it - it seems to be working).

I just hope to be able to auto-run some tests on commits. Once approved we have to extend it to other places.