cpp-common/bt2c: add `Uuid::Uuid(bt2c::CStringView)`

cpp-common/bt2c: add `Uuid::Uuid(bt2c::CStringView)`

Add a `Uuid` constructor that takes `bt2c::CStringView` and remove those
that take a `const char *` and `const std::string &`.  The implicit
conversions to `bt2c::CStringView` should be able to handle all those
types.

Change-Id: I1714fd2aa38c18a047b097908af7b52afebeab72
Signed-off-by: Simon Marchi <simon.marchi@efficios.com>
Reviewed-on: https://review.lttng.org/c/babeltrace/+/11953
Reviewed-by: Philippe Proulx <eeppeliteloop@gmail.com>
Tested-by: jenkins <jenkins@lttng.org>