Query documents from cache source

[magax]

Is there any way to set if we want to retrieve documents whether from server or cache? The same way we can do it with the Firestore instance method getDocuments(source: Source.cache). Thanks.

[MartinJLee]

In addition to this it would be nice if somehow it caches the last query area, and query only newly added area. Assume, the camera zoom level isn't changed, If the map area moved to the East, only query new three east areas then return with existing 6 areas (without the West 3 areas). Similar to all other axes and combinations. Also option with refresh all 9 queries.

[MartinJLee]

Duplicate https://github.com/DarshanGowda0/GeoFlutterFire/issues/78