BaseTools: Add mixed PCD support feature

BaseTools: Add mixed PCD support feature

Problem statement:
The current build system requires that a PCD must use the same access
method for all modules. A Binary Module may use a different PCD access
method than: 1.A source tree build it is integrated into. 2.Other Binary
Modules in platform build that use the same PCD.

Solution:
1. Source build:
No change. PCDs must use the same access method for building all Source
Modules.
2. Mixed Source & Binary Builds or Binary Only Builds:
1) Source Modules - No changes
2) Module that is interpreted as a Binary Module
a.DSC file may optionally override default value of PatchableInModule
PCDs in scope of Binary Module.
b.DSC file must declare DynamicEx PCD subtype for all DynamicEx PCDs
from Binary Modules.
c.FDF file must list Binary Module INF

Build update:
1. PCDs in a binary module are permitted to use the PatchableInModule
or DynamicEx access methods (the Binary INF clearly identifies the PCD
access method for each PCD). The build must support binary modules that
use the same or different PCD access method than the Source INFs or
other Binary INFs.
2. Build report list PCDs that have mixed PCD access methods.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Yonghong Zhu <yonghong.zhu@intel.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>