Need a way to have access to previousData from apollo-client's useQuery

[dguay]

Is your feature request related to a problem? Please describe.
In order to simulate apollo-client's old behavior where data is not set to undefined when fetching, we need to have access to previousData which is discussed here: apollographql/apollo-client#6603

Describe the solution you'd like
Add a new property previousResult to be returned by useQuery

Additional context
See discussion here: apollographql/apollo-client#6603

[JordanMajd]

This would be very useful