Control external displays (e.g., brightness) with DDC/CI

helloSystem should get the ability to control external displays (e.g., change the brightness).

Need to find out the state of the __Display Data Channel/Command Interface__ (DDC/CI) on FreeBSD.
https://www.reddit.com/r/freebsd/comments/ke51oq/controlling_displays_with_ddcci/ is wondering the same thing.

Wikipedia:
> DDC/CI (Command Interface) standard was introduced in August 1998. It specifies a means for a computer to send commands to the monitor, as well as receive sensor data from the monitor, over a bidirectional link. Specific commands to control monitors are defined in a separate Monitor Control Command Set (MCCS) standard version 1.0, released in September 1998.
> (...)
> Despite its **ubiquity in post-2016 displays**, DDC/CI is not generally used by the operating system by default for brightness control on external displays.[9] Additional software can be used to send commands to the display, but the degree of system integration vary.

https://www.ddcutil.com/release_notes/ says:

> Some configure options have been added, primarily in support of an as yet incomplete FreeBSD implementation. (Development is suspended **until FreeBSD's video drivers expose the I2C bus**.)

@rockowitz, the developer of `ddcutil`, has loaded the i2c drivers `iicbus.ko`, `iic.ko`, and video driver `nvidia.ko`, but the devices `/dev/iicN` do not exist (which I can confirm). Are we missing something or is additional development within FreeBSD necessary to access the i2c bus that is used for display communication?

https://forums.freebsd.org/threads/accessing-i2c-devices-from-userspace.77145/