OvmfPkg/OvmfPkg.ci.yaml: Add configuration for Ecc check

OvmfPkg/OvmfPkg.ci.yaml: Add configuration for Ecc check

Add configuration ExceptionList and IgnoreFiles for package config
files. So users can rely on this to ignore some Ecc issues.

Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Ard Biesheuvel <ard.biesheuvel@arm.com>
Signed-off-by: Shenglei Zhang <shenglei.zhang@intel.com>
Acked-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>