UnitTestFrameworkPkg: Add configuration for LicenseCheck in yaml file

Add configuration IgnoreFiles for package config files.
So users can rely on this to skip license conflict for
some generated files.

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