BaseTools: Add HOST_APPLICATION module type.

BaseTools: Add HOST_APPLICATION module type.

It can be used to indicate a module can be build to run
as OS application and run in OS environment.

Cc: Bob Feng <bob.c.feng@intel.com>
Cc: Liming Gao <liming.gao@intel.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Signed-off-by: Xiaoyu Lu <xiaoyux.lu@intel.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>