Implement exposure and whitebalance lock for gstreamer camera.

Change-Id: I58277d69c18ad2e31cad719a2dd6361c0c2d7e98
Reviewed-by: Yoann Lopes <yoann.lopes@theqtcompany.com>
Add support for face detection focus point mode to camerabin backend.

[ChangeLog][GStreamer] Implemented the face detection focus point mode
in the gstreamer camerabin backend.

Change-Id: Ia582d2fb5e74d5b438aa0038224c5e20e597d53e
Reviewed-by: Yoann Lopes <yoann.lopes@theqtcompany.com>
Add a color filter property to QCameraImageProcessing.

[ChangeLog] New color filter property for QCameraImageProcessing.

Change-Id: I999e349e3e4f284b533fa62ba50903fbd21cb400
Reviewed-by: Yoann Lopes <yoann.lopes@theqtcompany.com>