UnitTestFrameworkPkg: Add code coverage support for GCC

In order to collect code coverage after running executable
file, generate *.gcda and *.gcno file that require by lcov tool
to generate code coverage report.

Reviewed-by: Michael D Kinney <michael.d.kinney@intel.com>
Cc: Sean Brogan <sean.brogan@microsoft.com>
Cc: Bret Barkelew <Bret.Barkelew@microsoft.com>
Reviewed-by: Michael Kubacki <mikuback@linux.microsoft.com>
Signed-off-by: Gua Guo <gua.guo@intel.com>

UnitTestFrameworkPkg/UnitTestFrameworkPkg.ci.yaml

@@ -91,6 +91,7 @@
             "pytools",
             "NOFAILURE",
             "cmockery",
+            "cobertura",
             "DHAVE", # build flag for cmocka in the INF
             "gtest", # file name in GoogleTestLib.inf
             "corthon",      # Contact GitHub account in Readme