create presave validation hook for field_member_of and field_access_terms

[bseeger]

We should create a pre-save validation hook (maybe in islandora defaults) to prevent a user from putting values they don't have access to in those particular fields.

This would prevent a user from putting an object in a collection they don't have edit access to. This could help solve part of the problem outlined in #107. If we had a presave hook, it wouldn't matter so much what showed up in the UI, as this hook would catch any invalid values for that user.
This is also key to helping prevent the migration ingest from putting items in collections it shouldn't.

To be clear, if we have time to do one thing, this has a higher benefit then #107 as it will provide validation before saving the node. It will cover both the UI workflow and Ingest workflow paths.

[birkland]

It is unclear if this is a prerequisite for #114 or not.

[jordandukart]

So proof of concepted this quickly to do what was discussed as a MVP. Ran it past @bseeger and it seems to meet the intent of what's being intended for the time being.

To distill it out down leveraging the workbench_access_entity_access check to ensure that the user ingesting has the correct access to reference an object. If not a constraint validation is thrown and the field is targeted with an error message. To note this would also throw an error if validate: true was used in the context of a migration.

In the below scenario two collections are made: "Collection A" and "Collection B". The "test" user is given access to ingest into "Collection B" only.

When attempting to ingest into "Collection A":

Ingest into "Collection B" yields a new object.

Currently this code lives in the idc_ui_module but I'm unsure if this should be the permanent home for these types of customizations. @birkland can you confirm where you'd like these to live or if a new module should be created?

In regards to other work that distills out from this:

• An EntityReferenceSelectionPlugin such that these options are never present in the UI at all (estimate: 3-4 hours).
• A migrate plugin that ensures the user has access to a given entity (estimate: 3-4 hours).

[jordandukart]

As discussed on the iDC developer call I will go ahead and create a new module that will begin to contain more general hooks that aren't UI related.

[jordandukart]

Fixed in jhu-idc/idc_defaults#1.

[jordandukart]

As discussed in Slack tests are required for the above so this issue isn't ready for review yet.

[jordandukart]

field_access_terms handled in jhu-idc/idc_defaults#4.

[birkland]

All related PRs are merged, so this is done