[edk2-staging] Create new edk2-test branch

["Kinney, Michael D" <michael.d.kinney@intel.com>]

I am creating a new branch in edk2-staging called edk2-test.

The purpose of this branch is to develop a test harness, 
test case SDK, and library of test cases that can be used 
as part of edk2 validation.

The initial version of this test harness is compatible with
binary releases of the PI SCTs and UEFI SCTs, are native
edk2 packages with no dependencies on the EdkCompatibilityPkg,
and the test harness runs using the latest version of the
UEFI Shell.  

Additional work items:
* Update to take advantage of latest edk2 features/libraries.
* Update for all supported CPU types
* Update for all supported compilers
* Review initial test harness features and determine
  what features should be dropped and what new features
  should be added. 
* Determine where the test harness, test case SDK, and 
  test cases should live once the initial functional and 
  quality criteria are met.  Could be packages in the 
  edk2 repo or packages in a new edk2-test repo.  Other 
  options???
* Resolve compatibility issues with binary releases of the
  PI SCTs and UEFI SCTs.
* Update test harness to support PEI tests
* Update test harness to support Runtime tests
* Update test harness to support SMM tests
* Optimize performance of the test harness and tests.

Please contact me if you are interested in helping with the 
test harness, the test case SDK, or the development of 
test cases.

Thanks,

Mike