Ensure z_timestamp_new returns unique (and monotonically increasing) timestamp values #1102
Description
Describe the feature
Currently z_timestamp_new use gettimeofday function on unix systems (and probably even less precise functions for other platforms). For certain hardware this is not precise enough to guarantee unique timestamps - which leads to message loss for advanced_pub_sub when publishing at high frequency, since advanced subscriber retains at most one message per timestamp value when fetching history.