Initial support of make format for Windows

There are couple of caviats currently:

- The script requires system-wide Python 3 available in the current
  search PATH as python.exe.

  This will get addressed soon by distributing unpacked Python binary
  in our libraries.

- Since the libraries folder is to be known, this requires to have
  MSVC detected. Not too bad, since formatting is still way slower
  than detection, but still doesn't feel ideal.

make.bat

@@ -47,13 +47,18 @@ if "%BUILD_VS_YEAR%" == "" (
 	)
 )
 
+call "%BLENDER_DIR%\build_files\windows\check_libraries.cmd"
+if errorlevel 1 goto EOF
+
+if "%FORMAT%" == "1" (
+	call "%BLENDER_DIR%\build_files\windows\format.cmd"
+	goto EOF
+)
+
 call "%BLENDER_DIR%\build_files\windows\set_build_dir.cmd"
 
 echo Building blender with VS%BUILD_VS_YEAR% for %BUILD_ARCH% in %BUILD_DIR%
 
-call "%BLENDER_DIR%\build_files\windows\check_libraries.cmd"
-if errorlevel 1 goto EOF
-
 call "%BLENDER_DIR%\build_files\windows\check_submodules.cmd"
 if errorlevel 1 goto EOF