cpp-common/bt2: make `CommonClockClass::uuid` take a `bt2c::UuidView`

cpp-common/bt2: make `CommonClockClass::uuid` take a `bt2c::UuidView`

This, combined with a following patch that makes the constructors of
`bt2c::UuidView` implicit, makes it possible to pass a `bt2c::Uuid`
object directly to `CommonClockClass::uuid()`.

Change-Id: I336763e128bef5de8e208bc7fafcd9df59d7672a
Signed-off-by: Simon Marchi <simon.marchi@efficios.com>
Reviewed-on: https://review.lttng.org/c/babeltrace/+/11952
Tested-by: jenkins <jenkins@lttng.org>
Reviewed-by: Philippe Proulx <eeppeliteloop@gmail.com>