Support IsDelta for Edm function configuration

[xuzhg]

Short summary (3-5 sentences) describing the issue.

Assemblies affected

• OData recently added a feature to OASIS and AGS in order to flag a function as returning a delta payload. So, for example, a function could return the changes (delta) between 2 states.

Annotation Core.IsDelta
An action or function that returns a single entity or a collection of entities MAY return results as a delta payload. This is indicated by annotating the return type with the term Core.IsDelta.

This is the annotation added in the ODL:

https://github.com/OData/odata.net/blob/main/src/Microsoft.OData.Edm/Vocabularies/CoreVocabularies.xml#L530-L537

<Term Name="IsDelta" Type="Core.Tag" Nullable="false" DefaultValue="true" AppliesTo="ReturnType Parameter">
		<Annotation Term="Core.Description" String="The annotated Action or Function Parameter or Return Type is represented as a Delta payload" />
		<Annotation Term="Core.LongDescription">
			<String>
				The parameter or result is represented as a delta payload, which may include deleted entries as well as changes to related
				entities and relationships, according to the format-specific delta representation.
			</String>
		</Annotation>
	</Term>

Delta payloads represent changes between two versions of data and, in addition to current values, MAY include deleted entities as well as changes to related entities and relationships, according to the format-specific delta representation.
In the model builder, we'd support this annotation when building the Edm function.

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