Add support to the Runtime Defined Entities (RDE) framework with RDEs (3/3)

[adambarreiro]

Overview

This PR implements the foundations to onboard the RDE framework to the Terraform VCD Provider, by adding CRUD capabilities of RDE instances.

Detailed description

This PR adds the following features:

RDE types

• Adds the following methods to the existing DefinedEntityType type:
  • GetAllRdes to get all RDE instances from the given type, supports parameters like filtering.
  • GetRdeByName to get a unique RDE with given name. To make it unique it uses also the vendor+namespace+version from the given type, as one can have same name with this 3-tuple different combinations.
  • GetRdeById gets a unique RDE with given URN.
  • CreateRde to create a RDE instance. Creation is tricky, as it just returns a Task that remains at 1% progress in VCD. It will remain like that until it is "resolved" (see below method). So this method creates the RDE in an async way and recovers its refreshed state with an immediate get to return it.

RDE instances

• Adds the following methods to the new DefinedEntity type:
  • Resolve to resolve the entity. On creation, the RDE instance is just a Task that remains at 1% in VCD. It needs this method to be called to check the entity against the schema of the RDE type. If it's OK, the task is completed and RDE instance state is RESOLVED. Otherwise, it gets RESOLUTION_ERROR.
  • Update to update the entity. It is a bit smart to avoid errors if Name is not populated for update (ie: User doesn't want to update it, but it's mandatory). One use case for Update is to fix the JSON entity if we get a RESOLUTION_ERROR.
  • Delete to delete the entity. The entity needs to be resolved first.

Client

• Added OpenApiGetItemAndHeaders and OpenApiPostItemAndGetHeaders to retrieve all the response headers when performing a call to an OpenAPI endpoint.

[Didainius]

Looks good, I have one ask that is inline, but can also mention here for the Client.OpenApiX functions.

IMO they could all return all headers instead of querying one specific. The reason is that these are our core client functions and people (or we) might find the need to fetch multiple headers in future and that would require multiple API calls instead of one