Datasource: `prefect_account_user`

[parkedwards]

to be read down + assigned specific workspace or account accesses via role attachment

[parkedwards]

marking this as a WONTDO - general user fetch queries are not exposed by the API; instead, we have GET /account_memberships, which return users scoped to the account. It's also not immediately needed to be able to do user management via TF, as all users are added via invitation + their account roles can be managed from the account settings

[parkedwards]

on second thought, we actually do need this in order to assign workspace roles