MdeModulePkg: new PlatformHookLib library with depex of SerialPortPpi.

MdeModulePkg: new PlatformHookLib library with depex of SerialPortPpi.
 This library has one depex of SerialPortPpi. Then, the PEIM linked it has this depex so that it is dispatched after SerialPortPpi is installed. SerialPortPpi notifies the platform initialization done, then serial port will work.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Gao, Liming <liming.gao@intel.com>
Reviewed-by: Kinney, Michael D <michael.d.kinney@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@15782 6f19259b-4bc3-4df7-8a09-765794883524