Allow certain custom DAV props to be readable by everyone

[ChristophWurst]

This is a PoC to address the problems described in #27421.

Is this approach okay? Should we narrow down to specific paths only, like only expose calendar availability for inboxes? cc @blizzz @juliushaertl @tcitworld you are more experienced with DAV than me.

Fixes #27421

[tcitworld]

Is this approach okay?

Sounds good to me. Not sure if we need to narrow it down, but we certainly need to check that you can access calendar availability unlogged for instance.

[ChristophWurst]

we certainly need to check that you can access calendar availability unlogged for instance

What do you mean by unlogged?

[juliusknorr]

Is this approach okay? Should we narrow down to specific paths only, like only expose calendar availability for inboxes?

Should be fine as it is i'd say as there is only a fix list allowed for published properties.

[nickvergessen]

LGTM

[blizzz]

🐘