Add python batch wrappers

Bug:  777069
Change-Id: I32094c81f6050acc7e84d9eb9b1900071a937552
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/2748948
Commit-Queue: Josip Sokcevic <sokcevic@google.com>
Reviewed-by: Dirk Pranke <dpranke@google.com>

python-bin/python3.bat

+@echo off
+:: Copyright 2021 The Chromium Authors. All rights reserved.
+:: Use of this source code is governed by a BSD-style license that can be
+:: found in the LICENSE file.
+
+setlocal
+
+for %%d in (%~dp0..) do set PARENT_DIR=%%~fd
+for /f %%i in (%PARENT_DIR%\python3_bin_reldir.txt) do set PYTHON_BIN_ABSDIR=%PARENT_DIR%\%%i
+set PATH=%PYTHON_BIN_ABSDIR%;%PYTHON_BIN_ABSDIR%\Scripts;%PATH%
+"%PYTHON_BIN_ABSDIR%\python3.exe" %*
\ No newline at end of file

python2-bin/python2.bat

+@echo off
+:: Copyright 2021 The Chromium Authors. All rights reserved.
+:: Use of this source code is governed by a BSD-style license that can be
+:: found in the LICENSE file.
+
+setlocal
+
+for %%d in (%~dp0..) do set PARENT_DIR=%%~fd
+for /f %%i in (%PARENT_DIR%\python_bin_reldir.txt) do set PYTHON_BIN_ABSDIR=%PARENT_DIR%\%%i
+set PATH=%PYTHON_BIN_ABSDIR%;%PYTHON_BIN_ABSDIR%\Scripts;%PATH%
+"%PYTHON_BIN_ABSDIR%\python.exe" %*
\ No newline at end of file