Selectors: should consume platform flattening functions instead of jq expression syntax

[jakedoublev]

Background

As a result of the accepted ADR to employ flattening of an Entity Representation into known fields and values, otdfctl needs to consume the flattening functions instead of jq syntax when helping admins generate selectors for entitlement.

Acceptance Criteria

1. any jq evaluation is removed, and any docs are updated
2. flattening functions are employed in their place to provide context to the entitlement of a subject

[jakedoublev]

Blocked by opentdf/platform#644