device_manager: add device_get_uuid

device_manager: add device_get_uuid

Function that is working with DM target is located within
lib/activate directory.

This function is able to use cached  dm_device_list when possible
to quickly resolve checks for device's UUID.

Function can fully replace get_dm_uuid_from_sysfs() and instead
of syscalls for open/read/close get the UUID with single ioctl.

When there is cached dm devs list, we can get many UUID from
a single syscall.