Floss: Refactor formatting util of Uuid

This adds `Display` implementation for `Uuid` so that `Uuid`s can be
conveniently displayed in logs in human readable format.

This patch also refactors UuidHelper to reuse the same implementation
rather than duplicating it.

Bug: 217273154
Tag: #floss
Test: Manual - Build floss on Linux

Change-Id: Ib99c89721770bc9a6e38c329d21534584089b477