MdeModulePkg: Upstream SerialDxe from EmbeddedPkg

MdeModulePkg: Upstream SerialDxe from EmbeddedPkg

This Serial driver layers on top of a Serial Port Library instance
to produce serial IO protocol.

There is also another SerialDxe implementation in CorebootPayloadPkg,
but SerialDxe from EmbeddedPkg should be better that also consumes
the extended interfaces GetControl/SetControl/SetAttributes in
EmbeddedPkg/Include/Library/SerialPortExtLib.h for serial IO protocol.
And the extended interfaces GetControl/SetControl/SetAttributes in
EmbeddedPkg/Include/Library/SerialPortExtLib.h has been upstream to
MdePkg/Include/Library/SerialPortLib.h.

Cc: Michael D Kinney <michael.d.kinney@intel.com>
Cc: Liming Gao <liming.gao@intel.com>
Cc: Feng Tian <feng.tian@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Star Zeng <star.zeng@intel.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>
Reviewed-by: Michael Kinney <michael.d.kinney@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@18966 6f19259b-4bc3-4df7-8a09-765794883524