UnitTestFrameworkPkg: Add public and private interfaces

UnitTestFrameworkPkg: Add public and private interfaces

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

Add public interfaces for use by unit test implementations.

* Include path to cmocka library interfaces.
* PcdUnitTestLogLevel to set the unit test logging message
  level to filter log messages.

Add private interfaces that are used by UnitTestLib
implementations.

* [Private] UnitTestBootLib - Set boot next to continue unit
  tests across a reboot.
* [Private] UnitTestPersistenceLib - Save unit test framework
  state to a persistent storage device.
* [Private] UnitTestResultLib - Output unit test results to a
  console device.
* [Private] UnitTestFrameworkTypes.h - Internal structures
  used by UnitTestLib implementations to keep track if unit
  test frameworks, unit test suites, and unit tests along with
  the serialized storage format to save a unit test framework
  state to persistent storage.

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>