APIs that take KernelTimeout as a parameter can now query if an
absolute or relative timeout was requested. If the underlying API can
only use one type of timeout, the code will do a reasonable
conversion.

The goal is to eventually enable the possibility of using wait times
that are based on monotonic clocks that are safe against system clock
steps.

PiperOrigin-RevId: 508541507
Change-Id: Id08bf13515f3e1bfd78d88393cde98a6fd3ef72c