[edk2-rfc] [edk2-platforms] Add Features directory

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

Hello,

This RFC proposes adding a new directory to edk2-platforms called
"Features". The purpose of this directory is to add support code
for platform features. Intel would like to maintain features in the
form of feature packages in which a feature may be composed of
multiple libraries, modules, and/or other resources in the package.
The features Intel would like to support are generally intended to
be generic and compatible across a large number (if not all) of
Intel's open source platform code. Collaboration to expand support
of feature code is also welcome.

Reason for the new directory:
Currently some feature packages have started being maintained in
Platform/Intel such as DebugFeaturePkg. However, it would be
preferable to separate basic platform support packages such as
that in KabylakeOpenBoardPkg from generic feature packages.
This is especially true as the number of board support packages
and feature packages increase in Platform/Intel. The creation of
the Features directory would align with the logical separation of
package paths for other pieces needed to build an Intel firmware
in edk2-platforms:
  1. Basic platform support code: Platform/Intel
  2. Silicon initialization support code: Silicon/Intel
  3. Advanced feature support code: Features/Intel

The advanced feature is a concept introduced in EDK II Minimum
Platform. This concept is briefly described in the Platform/Intel
Readme.md:
https://github.com/tianocore/edk2-platforms/blob/master/Platform/Intel/Readme.md

On a related note, a preview of how the Features/Intel directory
might be used is available in the following fork:
https://github.com/makubacki/edk2-platforms/tree/advanced_feature_reorg

For this RFC, the request is simply for the creation of
edk2-platforms/Features to hold feature content.

Thanks,
Michael