Describes path operations descriptions from vocabulary annotations

[irvinesunday]

Closes #103
Closes https://github.com/microsoftgraph/microsoft-graph-devx-api/issues/529

• Retrieves operation descriptions from vocabulary annotations of IEdmVocabularyAnnotatable elements.
• Tests have been updated to validate this feature.

[xuzhg]

There's a line to set the description in the base class.

I don't know why do you want to rewrite it using the entity type.

Maybe you need to change that logic:

1. If we have description for the entity set, use it
2. otherwise, if we have description for entity type, use it
3. otherwise, leave it empty or use a default string.

[irvinesunday]

Are we not expecting a scenario where we have descriptions for both entity set and entity? In such a scenario, we would end up setting entity set descriptions for entities, even though they have their own annotated descriptions.

[xuzhg]

You mean for "single entity request, the annotation should from entity type?".

[irvinesunday]

Yes.

[xuzhg]

Typically, it should comes from entity set, not from entity type.
However, it seems we can't distinguish it from entity set or single entity.
So, I am ok for your changes.