Remove `entityVersion` from public APIs

### Describe the bug

`polaris-management-service.yml` uses a simple `entityVersion` approach to validate whether some update request, which includes the _full_ representation of the entity to be updated, can be performed or not.

The approach to be able to update a whole entity should be replaced with specific update operations per entity type. This is much easier to validate in service implementations and easier to understand from a client's point of view.

Start with polaris-management-service.yml and trace the service implementations that use the entityVersion update approach. Identify the entity-specific update operations required to replace whole-entity updates, and verify that the public API definitions and implementations no longer depend on entityVersion.

Written by the indexing model from the issue text.