Make the max authors setting optional and allow unlimited authors

[MoritzLost]

The Max Authors option in sections is marked as required, so it's not possible to not set a maximum:

There are many cases where we don't want or need a maximum, so we would like to just leave this option empty to allow unlimited authors. Right now, we have to set this option to an arbitrarily high number, which feels wrong.

Is there a technical reason for making this option required? Otherwise, I would suggest making this setting optional and default to not limiting the number of authors.

In addition, when creating a new section, the default for max authors should be unlimited instead of defaulting to one. Having a default of one makes sense when migrating from Craft 4, but not for newly created sections in Craft 5.