UnitTestFrameworkPkg/Test: Add unit test samples

https://bugzilla.tianocore.org/show_bug.cgi?id=2505



Add an implementation of a sample unit test that
demonstrates the use of the UnitTestLib services and
macros and supports being built for execution in a
host environment or for execution on a target in PEI,
DXE, SMM, or UEFI Shell.

Cc: Sean Brogan <sean.brogan@microsoft.com>
Cc: Bret Barkelew <Bret.Barkelew@microsoft.com>
Signed-off-by: Michael D Kinney <michael.d.kinney@intel.com>
Reviewed-by: Bret Barkelew <Bret.Barkelew@microsoft.com>