[image_picker] return error in the event that permissions are not granted

[jmacpherson]

Description

Throw an error when Android users deny permissions.

Related Issues

Fixes #34425

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[jmacpherson]

Thanks for your pull request. It looks like this may be your first contribution to a Google open source project (if not, look below for help). Before we can look at your pull request, you'll need to sign a Contributor License Agreement (CLA).

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Signed the CLA

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[cyanglaz]

maybe combine these 4 statements in the if (!permissionGranted) clause?

[jmacpherson]

Refactored per yr comment