Test if a specific extension is available

    CLI Example:

    .. code-block:: bash

        salt '*' postgres.is_available_extension

def is_available_extension(name,
                           user=None,
                           host=None,
                           port=None,
                           maintenance_db=None,
                           password=None,
                           runas=None):
    '''
    Test if a specific extension is available

    CLI Example:

    .. code-block:: bash

        salt '*' postgres.is_available_extension

    '''
    exts = available_extensions(user=user,
                                host=host,
                                port=port,
                                maintenance_db=maintenance_db,
                                password=password,
                                runas=runas)
    if name.lower() in [
        a.lower()
        for a in exts
    ]:
        return True
    return False