Cosmos: Add IS_DEFINED() function to cosmos provider

[RaymondHuy]

Resolve #17722

[AndriySvyryd]

@RaymondHuy Hello!

#17722 Is really about two scenarios: scalar properties and navigations to embedded entities. The latter can be a bit trickier to implement so for now you can throw in that case instead. Also it should be able to handle shadow properties so we'd also need an overload that takes a property name.

I'd like you to add these test cases:

• IsDefined in a Where call
• IsDefined in a Select call that creates an anonymous type
• IsDefined on a shadow property (Person.__id)
• IsDefined on a derived property (Bird.IsFlightless in InheritanceQueryCosmosTest)
• IsDefined on an embedded scalar property (OwnedPerson.PersonAddress.Country.Name in OwnedQueryCosmosTest)
• IsDefined on an embedded reference navigation (OwnedPerson.PersonAddress in OwnedQueryCosmosTest, can throw)
• IsDefined on an embedded collection navigation (OwnedPerson.Orders in OwnedQueryCosmosTest, can throw)
• IsDefined on a non-embedded navigation (Person.Orders, should throw)
• IsDefined on a non-existing property (Person.NonExisting, should throw)
• IsDefined on a non-mapped property (Person.__jObject, should throw)

[RaymondHuy]

@AndriySvyryd Thanks for your response. I will update test cases this weekend ;)

[AndriySvyryd]

I'm closing this PR since there hasn't been any activity lately. Feel free to submit a new one once you've addressed the above.