Resolve "Refactor fwCore::HiResClock"

What does this MR do?

Closes #56 (closed)

HiResClock is currently implemented differently on Windows and other systems:

• Windows uses the QueryPerformanceCounter Windows API function.
• Other systems use the gettimeofday function.

Thix MR fix that by using std::chrono.

How to test it?

Launch fwCoreTest.

Additional tests to run

• Build on Windows
• Build on Linux
• Build on OSx