Timestamped logging macro for elapsed physical time

[adi-65-ray]

This PR is a fix for #395.

I have implemented a macro which prepends the physical lapsed time to debug messages
LF_TIMESTAMP_PRINT_DEBUG in logging_macros.h
I have also included a test code to test the functionality of the macro to check its expected output.

expected output:
DEBUG: Start time: -9223372036854775808
DEBUG: [-7464962496372149757] [Test case: 0]testing timed debug prints
DEBUG: [-7464962491372064629] [Test case: 1]testing timed debug prints
DEBUG: [-7464962486371771465] [Test case: 2]testing timed debug prints
DEBUG: [-7464962481371438023] [Test case: 3]testing timed debug prints
DEBUG: [-7464962476371116940] [Test case: 4]testing timed debug prints
DEBUG: [-7464962471370813344] [Test case: 5]testing timed debug prints
DEBUG: [-7464962466370645568] [Test case: 6]testing timed debug prints
DEBUG: [-7464962461370410362] [Test case: 7]testing timed debug prints
DEBUG: [-7464962456370065744] [Test case: 8]testing timed debug prints
DEBUG: [-7464962451369754731] [Test case: 9]testing timed debug prints

[hokeun]

This is a great start. Thanks! I left some suggestions.

[hokeun]

Just to provide the context @adi-65-ray (Aditya Ray) is an M.S. student at ASU, and he kindly volunteered to fix this issue. This PR will be his very first contribution.

[edwardalee]

This is a nice feature to have, but there remain some subtleties. If we can resolve these, it might be nice to have this be part of the LF_PRINT_DEBUB macro rather than being a whole new macro.

[edwardalee]

LGTM!
(Modulo getting the tests to pass)

[hokeun]

👍