BaseTools/Scripts: Porting PackageDocumentTools code to use Python3

Porting PackageDocumentTools code to support python2 and python3

Cc: Bob Feng <bob.c.feng@intel.com>
Cc: Liming Gao <liming.gao@intel.com>
Cc: Yonghong Zhu <yonghong.zhu@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Zhiju.Fan <zhijux.fan@intel.com>
Tested-by: Laszlo Ersek <lersek@redhat.com>
Tested-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Liming Gao <liming.gao@intel.com>
Reviewed-by: Bob Feng <bob.c.feng@intel.com>

BaseTools/Scripts/PackageDocumentTools/plugins/EdkPlugins/edk2/model/inf.py

@@ -11,9 +11,9 @@
 # WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
 #
 
-import plugins.EdkPlugins.basemodel.ini as ini
+from ...basemodel import ini
 import re, os
-from plugins.EdkPlugins.basemodel.message import *
+from ...basemodel.message import *
 
 class INFFile(ini.BaseINIFile):
     _libobjs = {}