Support Snapdragon™ Game Super Resolution (SGSR)

## What problem does this solve or what need does it fill?

Bevy currently only has DLSS upscaler.

## What solution would you like?

Add https://github.com/SnapdragonGameStudios/snapdragon-gsr upscaler.

It is licensed under BSD 3-clause and the shaders look quite simple and should be corss-platform.

## What alternative(s) have you considered?

Don't support it. It could serve as a community plugin.

Start by reviewing the Snapdragon Game Super Resolution repository linked in the issue and comparing its shader and licensing requirements with Bevy's existing DLSS upscaler support. Determine the integration scope and platform expectations, then verify that Bevy can expose SGSR as an upscaler and that the relevant cross-platform behavior works.

Written by the indexing model from the issue text.