[Add polygon] When drawing, last edge is only updated when map stops moving

[gino-m]

trafficstars

We should update the edge on camera move rather than on drag finished.

@shobhitagarwal1612 Also related to your last PR.. could you PTAL?

[shobhitagarwal1612]

SGTM

[shobhitagarwal1612]

I created a sample PR with the changes. It shows some performance issues. Possible reasons:

1. We create a new instance of Point and CameraPosition on each position update.
2. PolygonDrawingView listens to position updates regardless of visibility.

[gino-m]

Is GoogleMapsAdapter#setMapFeatures updating only the changed features as it should, or is it updating all features on each change?

[shobhitagarwal1612]

Features are only being updated when the map stops moving. IMO, just the unregulated creation of objects on each camera motion is behind the cause. (Plus a couple of more optimisations)

[scolsen]

@shobhitagarwal1612 for current status -- would you like to take this on as well?

[shobhitagarwal1612]

Closing in favor of https://github.com/google/ground-android/issues/1839