Improve error handling for updating valkyrie collections

[elrayle]

Description

When processing an update for a valkyrie collection, the updated collection instance was not being handled correctly when failures occurred.

If the form validation failed, the updates were not processed and after_update was called instead of after_update_error.

If the transactions failed, @collection was set to false by .value_or before it called `after_update_error.

Similar issues were happening with the create process that were fixed in PR #5604.

WAS:

form.validate(collection_params) &&
          @collection = transactions['change_set.update_collection']
                        .call(form)
                        .value_or { return after_update_error }
after_update

Now, the form validation is processed before setting @collection. If a failure occurs, the process is aborted and calls after_update_errors. Likewise, if there is a failure during the transaction process, after_update_errors is called to process the error and redisplay the edit form. @collection is only updated if there are no form or transaction failures.

NOTE: This PR also moves after and before methods for update to private, deprecating the public versions. This is consistent with the pattern used in works and for create collection.

Related work

The approach is based on the same change that was made for works in PR #5448.

This is follow-on work for the changes to the create collection process in PR #5604.

@samvera/hyrax-code-reviewers

[cjcolvar]

Looks good. I had a couple questions about what might be slight changes in behavior.

[cjcolvar]

This looks great!