Fix errors that occurs when the path to python.exe includes space characters

[homuler]

Currently, when PYTHON_BIN_PATH includes space characters, the following command will fail (on Windows).

Rem Assume that Python is installed to `C:\Program Files (x86)\Python`.
bazel build -c opt --action_env PYTHON_BIN_PATH="C://Program Files (x86)//Python//python.exe" //tensorflow/lite:framework

ERROR: An error occurred during the fetch of repository 'local_execution_config_python':
   Traceback (most recent call last):
        File "C:/users/homul/sources/tensorflow/third_party/py/python_configure.bzl", line 210, column 33, in _create_local_python_repository
                python_lib = _get_python_lib(repository_ctx, python_bin)
        File "C:/users/homul/sources/tensorflow/third_party/py/python_configure.bzl", line 130, column 21, in _get_python_lib
                result = execute(repository_ctx, [python_bin, "-c", cmd])
        File "C:/users/homul/sources/tensorflow/third_party/remote_config/common.bzl", line 230, column 13, in execute
                fail(
Error in fail: Repository command failed
'C:\Program' is not recognized as an internal or external command,
operable program or batch file.

This PR makes it sure that the command path will be quoted if it includes space characters.

[angerson]

Thanks!