Added SensorConfiguration struct

[Alexei-Kornienko]

With a certain camera:

rpicam-hello --list-cameras
Available cameras
-----------------
0 : imx219 [3280x2464 10-bit RGGB] (/base/axi/pcie@120000/rp1/i2c@88000/imx219@10)
    Modes: 'SRGGB10_CSI2P' : 640x480 [206.65 fps - (1000, 752)/1280x960 crop]
                             1640x1232 [41.85 fps - (0, 0)/3280x2464 crop]
                             1920x1080 [47.57 fps - (680, 692)/1920x1080 crop]
                             3280x2464 [21.19 fps - (0, 0)/3280x2464 crop]
           'SRGGB8' : 640x480 [206.65 fps - (1000, 752)/1280x960 crop]
                      1640x1232 [83.70 fps - (0, 0)/3280x2464 crop]
                      1920x1080 [47.57 fps - (680, 692)/1920x1080 crop]
                      3280x2464 [21.19 fps - (0, 0)/3280x2464 crop]

You cannot select exact sensor mode by providing a pixel format. Cause when I set pixel format to RGGB expecting to select SRGGB8 1640x1232 [83.70 fps - (0, 0)/3280x2464 crop] libcamera selects 'SRGGB10_CSI2P' 1640x1232 [41.85 fps - (0, 0)/3280x2464 crop] sensor mode cause it's fully compatible in every part (cause both of them are extended to RGGB16).

This struct allows to define a specific sensor configuration and provide it to camera configuration before validate call. It allows user to specify exact sensor mode that needs to be used:

        let mut cfgs = camera.generate_configuration(&[StreamRole::Raw])
            .context("generate camera configuration")?;

        let mut sensor_mode = SensorConfiguration::new();
        sensor_mode.set_bit_depth(SENSOR_BIT_DEPTH);
        sensor_mode.set_output_size(FRAME_WIDTH, FRAME_HEIGHT);
        cfgs.set_sensor_configuration(sensor_mode);

        let mut config = cfgs.get_mut(0).unwrap();
        config.set_pixel_format(PIXEL_FORMAT_RAW);
        config.set_size(Size { width: FRAME_WIDTH, height: FRAME_HEIGHT });
        config.set_buffer_count(NUM_BUFFERS);

        match cfgs.validate() {
            CameraConfigurationStatus::Valid => log::debug!("Camera configuration valid!"),
            CameraConfigurationStatus::Adjusted => log::debug!("Camera configuration was adjusted: {:#?}", cfgs),
            CameraConfigurationStatus::Invalid => bail!("Error validating camera configuration"),
        }

For my setup it does exactly what I want - select exact sensor mode.

[chemicstry]

Thanks!