This pr addresses#3402 by allowing all of the zarr-specific exceptions take a single argument, which will be treated as a pre-formatted message. The old behavior, in which an exception would take multiple arguments and use them to format a canned message, is still available by passing in multiple arguments. I don't know how to deprecate this visibly, but I also suspect the API ofzarr.errors is not a load-bearing member for many downstream projects.

While changing the exceptions inzarr.errors, I found more exceptions defined inzarr.core.indexing. I moved those definitions tozarr.errors, because all our errors should be defined in one place, barring a strong reason otherwise. Had all the errors been defined in place, I wouldn't have needed to use a text search to discover the additional errors inzarr.core.indexing.