add --skip-install option to prevent running pip in launch.py and speedup launch a bit

git = os.environ.get('GIT', "git")

index_url = os.environ.get('INDEX_URL', "")

stored_commit_hash = None

skip_install = False

def commit_hash():

def run_pip(args, desc=None):

    if skip_install:

        return

    index_url_line = f' --index-url {index_url}' if index_url != '' else ''

    return run(f'"{python}" -m pip {args} --prefer-binary{index_url_line}', desc=f"Installing {desc}", errdesc=f"Couldn't install {desc}")

def prepare_environment():

    global skip_install

    torch_command = os.environ.get('TORCH_COMMAND', "pip install torch==1.12.1+cu113 torchvision==0.13.1+cu113 --extra-index-url https://download.pytorch.org/whl/cu113")

    requirements_file = os.environ.get('REQS_FILE', "requirements_versions.txt")

    commandline_args = os.environ.get('COMMANDLINE_ARGS', "")

    sys.argv, reinstall_xformers = extract_arg(sys.argv, '--reinstall-xformers')

    sys.argv, update_check = extract_arg(sys.argv, '--update-check')

    sys.argv, run_tests, test_dir = extract_opt(sys.argv, '--tests')

    sys.argv, skip_install = extract_arg(sys.argv, '--skip-install')

    xformers = '--xformers' in sys.argv

    ngrok = '--ngrok' in sys.argv