Re-think how change resources should work for the handler

Previously, the handler was able to add resources regardless of if they had the same form and/or workflow as the original resource or not. This feature was removed during the summer by another change (changing the dropdown menu component), allowing the handler to only add resources with the same form and workflow as the original resource.

Re-think how change resources should work for the handler and re-implement the feature if needed.

Some question to think about:

- What if the handler makes a mistake and adds a resource that has a completely different form, thinking that the form is close enough to the form that the user has filled? Should we protect the handler from making such mistakes?

- What if a resource with a different workflow is added, having a different set of handlers? Should the handlers of the other workflow be notified? Should the system ensure that all granted entitlements for resources with a certain workflow go through the handlers of that particular workflow?

- Should the system ensure that the form always matches the entitled resources exactly, as it currently ensures that the accepted licenses match the entitled resources exactly?

- Is the feature useful enough in practice to warrant the extra complexity and possible confusion to the handler/applicant that may ensue?

Start by reviewing the handler's resource-add flow and the dropdown menu change that removed cross-form or cross-workflow selection. Trace how forms, workflows, handlers, and entitlements are currently related, then resolve the listed policy questions with maintainers. Done means an agreed behavior and implementation scope; the issue names no files or tests.

Written by the indexing model from the issue text.