Migrate CameraX snippets

[barbaralaw]

Code snippets are for:

• https://developer.android.com/media/camera/camerax/analyze
• https://developer.android.com/media/camera/camerax/architecture
• https://developer.android.com/media/camera/camerax/camera1-to-camerax
• https://developer.android.com/media/camera/camerax/configuration
• https://developer.android.com/media/camera/camerax/extensions-api
• https://developer.android.com/media/camera/camerax/mlkitanalyzer
• https://developer.android.com/media/camera/camerax/orientation-rotation
• https://developer.android.com/media/camera/camerax/preview
• https://developer.android.com/media/camera/camerax/transform-output
• https://developer.android.com/media/camera/camerax/video-capture

This builds on @katherinekuan's first pass (her commit is kept with its original authorship). Follow-up commits move the files into the existing :camera module (com.example.camera.snippets.camerax), switch new dependencies to the version catalog, and bring the code inside every region tag back in line with what the guide pages above print.

camera/src/main/res/layout/activity_main.xml is required for the Kotlin snippets to compile: the page code references R.layout.activity_main, R.id.previewView, and R.id.preview_view, which also forces the file name. It has no region tag; the preview page's XML layout block stays hardcoded because it prints xmlns and size attributes the compiling layout can't hide.

List of modifications:

• All pages: Added a full stop to comments that lacked one; formatted with spotless (some wrapped lines inside regions changed indentation, and stray semicolons were removed); whole-line .../… elisions became // ... comments, or plain [START_EXCLUDE] blocks (rendered as ...) where the hidden code is needed to compile.
• Analyze page: Region now starts at val imageAnalysis =; restored this as the lifecycle owner; the "insert your code here" comment is normalized to // Insert your code here.
• Architecture page: Updated the custom LifecycleOwner to the current API (override val lifecycle, currentState =); getAvailableCameraInfos() → availableCameraInfos (CameraProvider is Kotlin in CameraX 1.6).
• Camera1-to-camerax page:
  • getAvailableCameraInfos() → availableCameraInfos. getCameraSelector() is kept as printed, because the prose names CameraInfo.getCameraSelector() and CameraInfo is still a Java interface.
  • Fixed requireContext(), the *useCases spread, a stray }), return@first, Observer<Int>, missing Boolean returns, and private var inside function bodies.
  • Tap-to-focus: meteringPoint → focusPoint and result → focusResult, the names the snippet itself declares.
  • Pinch-to-zoom: SimpleOnGestureListener → ScaleGestureDetector.SimpleOnScaleGestureListener, the listener that defines onScale().
  • Take photo with CameraProvider: the page's takePicture(...) arguments are a plain exclude, so the page still shows .... The arguments, commas, and callback object are hidden together so the rendered code stays balanced.
  • The published page drops Kotlin generics in several blocks (unescaped <…> in the HTML); the migrated snippets show them: Observer<Int>, Observer<ZoomState>, Array<UseCase>, VideoCapture<Recorder>.
• Configuration page:
  • ImageCapture.Builder example: the page's setFlashMode(...) / setTargetAspectRatio(...) placeholders are kept visible with a silent twin (page lines in a silent block comment, compiling values in a silent exclude), so the rendered code matches the page and both calls still compile.
  • MeteringPoint example: the page declares val meteringPointFactory twice. The second declaration line is kept visible with the same silent-twin approach, so the SurfaceOrientedMeteringPointFactory call still compiles without a redeclaration.
  • ?: return for a nullable; Kotlin lambda + .toFloat() in the metering snippet; fixed (x1, y1), or, and a missing ).
• Extensions-api page: Printed imports kept as // import ... inside the region, with the real imports at the top of the file.
• Mlkitanalyzer page: Added androidx.camera:camera-mlkit-vision and com.google.mlkit:barcode-scanning 17.3.0 to the catalog and :camera.
• Orientation-rotation page: The two identical ImageProxy rotation blocks share one region tag; the three CameraActivity examples are each wrapped in a private object; AppCompatActivity → ComponentActivity in the three printed CameraActivity classes.
• Preview page: Printed imports kept as // import ...; added the missing super.onCreate(savedInstanceState); AppCompatActivity → ComponentActivity in the printed MainActivity.
• Transform-output page: Removed a stray ; and adjusted indentation and spacing (fun ...(): Matrix).
• Video-capture page: Formatting only.
• Build: All Activity classes in the CameraX files (hidden wrappers and the four printed classes above) extend ComponentActivity, so :camera doesn't need androidx.appcompat (consistent with Migrate Camera2 hardcoded snippets #1134). Neither page's prose names AppCompatActivity. :camera:spotlessCheck, :camera:compileDebugKotlin, and :camera:lintDebug pass.

Snippets not migrated (left hardcoded on the guide pages):

• Gradle dependency blocks and AndroidManifest.xml entries.
• Camera1 "before" code on camera1-to-camerax (older API shown for migration contrast).
• Camera1-to-camerax CameraController video recording snippet, because it uses APIs removed from CameraX.
• Orientation-rotation Exif snippets, because they use the restricted androidx.camera.core.impl.utils.Exif.
• View Binding snippets (architecture, camera1-to-camerax, configuration seek bar, video-capture list), because the :camera module doesn't use View Binding.
• Preview page XML layout (see above).

Documentation CL: http://cl/988523079