[google_maps_flutter] Add a bitmap descriptor that is aware of scale

[iskakaushik]

Description

This makes it so you can create BitmapDescriptors that are aware of screen dpi

Related Issues

• Google Maps Plugin - Marker icon has incorrect size on iOS flutter#27393

Checklist

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Breaking Change

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[iskakaushik]

We do not need to scale images in android because Bitmap doesn't scale images by default

[cyanglaz]

The code looks good (Just some nits), but I feel like [BitmapDescriptor] can totally be a separate plugin so people can use it for anything not just google map. @amirh @collinjackson

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[iskakaushik]

@cyanglaz what use case were you thinking of?

Also, we can always factor it out to a different plugin if need be. For now, google maps is the only consumer of it, so might as well leave it here.

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[cyanglaz]

LGTM

[JRR-OSU]

@iskakaushik

I am not able to get the Size param to do anything when creating an ImageConfiguration, or modifying the default one shown in the example. On Android my 64x64 marker is still really small. On both platforms modifying Size does nothing. Is there something I'm missing?