service/client: Add start-adv -u flag

Added the -u flag that allows passing a UUID in string representation
(16-bit, 32-bit, and 128-bit) to be advertised as long as all fields
fit inside the data.

Bug: 24247700

Change-Id: I3e572db31b84f1e010ba19ab5a51d00c563bb3b7
1 file changed