chore: misc updates and improvements made while you were gone, take 2

[sverrehu]

This is a "While you were gone, take 2".

• Updates certain GitHub actions to get rid of a lot of warnings.
• Updates most dependencies to the most recent version.
• When pretty-printing JSON, split arrays in one entry per line. This makes it much easier to spot differences in .cluster-state.
• Display the warning for disabled remote state verification just once.
• Make it possible to disable warnings printed when projects contain no topics.
• Make it possible to disable warnings printed when streams have no writers.

This PR is one commit behind master, since the most recently merged contribution breaks the unit tests. (Maybe revert it to have unit tests work again.)

[sverrehu]

Hi, @purbon! As noted in the description, the tests will continue to fail for this PR (and others) as long as the previous merge to master is not reverted or fixed by another merge.