Add "config file" support

[yarikoptic]

not yet sure about all "features" but such config file should support but it must allow to specify

• which checks for which paths to ignore

This is largely inspired by config file in bids-validator, see https://github.com/bids-standard/bids-validator#configuration

It is needed since some of such ignores are "per dataset" and thus it should be possible to specify what to ignore in a specific dataset (or dandiset) in DANDI land, instead of relying on user to know what command line options to provide.