Adds a kata-io-compatible client that returns data from a slice and
sends writes to the kernel (if possible) or discards them. This will
be used for running cli scripts and for platforms that do not have a
uart device/driver.
Change-Id: I84facebf16eb9b6692e872e930db027998dd160f
GitOrigin-RevId: 11a3502fb2f8716f9d1a204519b5e93162274590