Check feature enabled on isCameraRunningAndWindowingModeEligible.

This method is used in shouldOverrideMinAspectRatioForCamera, which
should return false if the feature is disabled, or if the app is not
opted-in.

Flag: com.android.window.flags.enable_camera_compat_for_desktop_windowing
Bug: 368573687
Test: atest WmTests:CameraCompatFreeformPolicyTests
Change-Id: Iff542ec54a051ed11d32519b62f13a1d856cbfa3