Add support for specifying lens facing for test camera

Also make parsing command line args bit more robust.
Bug: 301023410
Test: atest virtual_camera_tests

Change-Id: If166b1a5bbada843b91ec1530629051b65df084c
diff --git a/services/camera/virtualcamera/util/MetadataUtil.h b/services/camera/virtualcamera/util/MetadataUtil.h
index 5d16506..cee867e 100644
--- a/services/camera/virtualcamera/util/MetadataUtil.h
+++ b/services/camera/virtualcamera/util/MetadataUtil.h
@@ -469,6 +469,9 @@
 std::optional<GpsCoordinates> getGpsCoordinates(
     const aidl::android::hardware::camera::device::CameraMetadata& metadata);
 
+std::optional<camera_metadata_enum_android_lens_facing> getLensFacing(
+    const aidl::android::hardware::camera::device::CameraMetadata& metadata);
+
 }  // namespace virtualcamera
 }  // namespace companion
 }  // namespace android