.pytool/Plugin: Add a plugin EccCheck

.pytool/Plugin: Add a plugin EccCheck

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=2606
EccCheck is a plugin to report Ecc issues for code in pull request
, which will be run on open ci.
But note not each kind of issue could be reported out.
It can only handle the issues, whose line number in CSV report
accurately map with their code in source code files. And Ecc issues
about comments can also be handled.

Cc: Sean Brogan <sean.brogan@microsoft.com>
Cc: Bret Barkelew <Bret.Barkelew@microsoft.com>
Cc: Michael D Kinney <michael.d.kinney@intel.com>
Cc: Liming Gao <liming.gao@intel.com>
Signed-off-by: Shenglei Zhang <shenglei.zhang@intel.com>