[edk2-platforms] [RFC] Migrate devel-MinPlatform branch to master branch

["Kubacki, Michael A" <michael.a.kubacki@intel.com>]

Hello,

This RFC proposes moving the content on the devel-MinPlatform branch
in the edk2-platforms repository to the master branch in the
edk2-platforms repository.

The devel-MinPlatform branch has been used for the initial development
of an EDK II based platform design referred to as "Minimum Platform". 
This design is intended to provide a structured approach to introducing
Intel platform code into open source in a consistent manner.

For more information about the EDK II Minimum Platform, please refer to 
the Readme.md in devel-MinPlatform.
https://github.com/tianocore/edk2-platforms/blob/devel-MinPlatform/ReadMe.md

The following packages would be added in Platform/Intel:
  * Generic packages:
     * AdvancedFeaturePkg
     * MinPlatformPkg
  * Board-specific packages:
     * ClevoOpenBoardPkg
     * KabylakeOpenBoardPkg
     * PurleyOpenBoardPkg

The following packages would be added in Silicon/Intel:
 * KabylakeSiliconPkg
 * LewisburgPkg
 * PurleyRcPkg
 * PurleySktPkg

The following growth is expected over time:
 * Platform/Intel - Additional board packages for Intel reference boards 
    including support for some pre-existing product releases
 * AdvancedFeaturePkg - Additional modular features capable of being used
    in board packages
 * Silicon/Intel - Additional silicon packages roughly keeping 1:1 parity
    with board packages

We hope the content will enable others to add new board packages and advanced
features over time.

The result of the change is available here for reference:
https://github.com/lgao4/edk2-platforms

Regards,
Michael