EmulatorPkg: Pipeline: Resolve SecureBootVariableLib dependency

EmulatorPkg: Pipeline: Resolve SecureBootVariableLib dependency

The new changes in SecureBootVariableLib brought in a new dependency of
PlatformPKProtectionLib.

This change added the new library instance from SecurityPkg to resolve
pipeline builds.

Cc: Andrew Fish <afish@apple.com>
Cc: Ray Ni <ray.ni@intel.com>
Signed-off-by: Kun Qin <kuqin12@gmail.com>
Reviewed-by: Ray Ni <ray.ni@intel.com>
Reviewed-by: Jiewen Yao <Jiewen.yao@intel.com>
Acked-by: Michael Kubacki <michael.kubacki@microsoft.com>