Remove entityName, entityDisplayName

[foundrytom]

What

Remove ManagerInterface.entityDisplayName, and replace with a DisplayName trait in MediaCreation.

Why

Now we have a composable traits system, that allows a host to express the entity data they need, in a concise (and reflectable form, via managementPolicy), making the entity name a first-class concept has several flaws:

• It requires an additional API call to service, which can add non-trivial work.
• In many situations where it would be called, a resolve call would also be made to provide other information.
• It prohibits the addition of additional fields, eg, providing a shot name and a long name (maybe for UI + tooltip).
• Fewer API methods to maintain.

By making it a trait, we can hopefully reduce the total number of API calls, and add more flexibility as to how this may need to evolve over time (It's also one less method to maintain).

Potential downsides:

• Another trait to consider in resolve adds to implementation complexity.
• Less discoverable.
• The implementation of entityDisplayName could be individually optimized.