BaseTools: Update Build tool to support multiple workspaces

WORKSPACE is still kept.
New PACKAGES_PATH is introduced to specify the additional WORKSPACEs.
In PACKAGES_PATH, ';' is separator in Windows, ':' is separator in Linux.

Build directory is in WORKSPACE. Package, BaseTools and Conf directory
will be found from WORKSPACE and PACKAGES_PATH.

In implementation, BaseTools adds MultipleWorkspace class for
the file path conversion from WORKSPACE and PACKAGES_PATH.

Verify two tree layouts.
Root\edk2\MdePkg
Root\edk2\MdeMdeModulePkg
Root\edk2\...
1. set WORKSPACE=Root\edk2
2. set WORKSPACE=Root, and set PACKAGES_PATH=Root\edk2

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Li YangX <yangx.li@intel.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>

git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@18579 6f19259b-4bc3-4df7-8a09-765794883524

BaseTools/Source/Python/Common/String.py

@@ -24,6 +24,7 @@ import GlobalData
 from BuildToolError import *
 from CommonDataClass.Exceptions import *
 from Common.LongFilePathSupport import OpenLongFilePath as open
+from Common.MultipleWorkspace import MultipleWorkspace as mws
 
 gHexVerPatt = re.compile('0x[a-f0-9]{4}[a-f0-9]{4}$', re.IGNORECASE)
 gHumanReadableVerPatt = re.compile(r'([1-9][0-9]*|0)\.[0-9]{1,2}$')
@@ -305,6 +306,11 @@ def NormPath(Path, Defines={}):
         # To local path format
         #
         Path = os.path.normpath(Path)
+        if Path.startswith(GlobalData.gWorkspace) and not os.path.exists(Path):
+            Path = Path[len (GlobalData.gWorkspace):]
+            if Path[0] == os.path.sep:
+                Path = Path[1:]
+            Path = mws.join(GlobalData.gWorkspace, Path)
 
     if IsRelativePath and Path[0] != '.':
         Path = os.path.join('.', Path)
@@ -702,7 +708,7 @@ def RaiseParserError(Line, Section, File, Format='', LineNo= -1):
 # @retval string A full path
 #
 def WorkspaceFile(WorkspaceDir, Filename):
-    return os.path.join(NormPath(WorkspaceDir), NormPath(Filename))
+    return mws.join(NormPath(WorkspaceDir), NormPath(Filename))
 
 ## Split string
 #