…JpegImageQuality (#11616)

Implements the `setJpegImageQuality` API (landed in the platform interface via #11454) across all camera platform implementation packages, allowing control of JPEG compression quality (1-100) for still image capture.

This is the follow-up implementation PR as requested in #11155; it does not include `camera_platform_interface` changes. The app-facing `camera` package will be submitted in a separate PR after these implementation packages are published.

Packages changed:
- `camera_android`
- `camera_android_camerax`
- `camera_avfoundation`

Part of flutter/flutter#183229

## Pre-Review Checklist

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…o auto-focus point (#11884)

Adds the missing `isEmpty` guard to the `FocusMode.auto` branch of `AndroidCameraCameraX.setFocusMode`, which read `meteringPointsAf.first` unconditionally and threw `StateError: Bad state: No element` when the current focus-and-metering action had no auto-focus point. 

The `FocusMode.locked` branch already guards this; the `auto` branch did not.

Fixes flutter/flutter#187782

## Pre-Review Checklist

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[^1]: Regular contributors who have demonstrated familiarity with the repository guidelines only need to comment if the PR is not auto-exempted by repo tooling.