Use Postgres UUID type to store UUIDs

It looks like various database columns are storing UUIDs as strings:

* `actees.id`
* `actees.parent`
* `actors.acteeId`
* `assignments.acteeId`
* `audits.acteeId`
* `datasets.acteeId`
* `entity_def_sources.type`
* `form_attachments.acteeId`
* `forms.acteeId`
* `grants.acteeId`
* `projects.acteeId`

Storing UUIDs as `UUID` instead of `VARCHAR(36)`/`CHARACTER VARYING (36)` is likely to (marginally?) improve query speed and RAM usage.

Start by locating the database schema or migrations that define the listed tables and columns, including actees.id, actees.parent, and the various acteeId fields. Check how each is currently stored and map the required schema changes. Done means the listed UUID columns use PostgreSQL's UUID type consistently and the migration completes successfully.

Written by the indexing model from the issue text.