libdm: LoopControl::Add/Remove(id)

This new methods wraps ioctl(LOOP_CTL_ADD/LOOP_CTL_REMOVE) with a given
ID.

Bug: 413174275
Flag: com.android.apex.flags.mount_before_data
Test: libdm_test
Change-Id: Id8b95180771590ac10e207212a80bd08f30d95d8