ResponseHandler should look at Content-Type before trying to deserialize as JSON

[darrelmiller]

See microsoftgraph/msgraph-sdk-dotnet#534

We should only pass content on to the Serializer if the content-Type is application/json otherwise we need to find some other way of returning the payload.

This is going to need to be fixed in the snippet generator as this is wrong https://docs.microsoft.com/en-us/graph/api/reportroot-getmailboxusagedetail?view=graph-rest-1.0&tabs=csharp#request

AB#7197

[andrueastman]

This should be resolved with Kiota as the ParseNodeRegistry uses the Content-Type to determine the factory to use to handle the response.

Ref here

[andrueastman]

Closing this now as this is validated with the latest kiota based preview versions