The checks `cluster_config_has_changed` and `node_tl_has_changed` use a
state file to store the previous value of the config hash and the
timeline.
Previously the check would fail if something changed, but the new value
would be saved directly. This behavious has changed. The new value
is saved only if `--save` is passed to the check.
The mimics the way [check_pgactivity] manages this kind of checks.
[check_pgactivity]: https://github.com/OPMDG/check_pgactivity
Stop using ctx.parent.params to get the verbose and timeout parameters
parsed in main and use ctx.obj instead.
ctx.parent.params is typed as Optional[Context] which forces us to test
if it's NULL before using it. It's useless in our case because we know
it's not empty and the resulting code is ugly.
The mypy ierror.
Item "None" of "Optional[Context]" has an attribute "params"
[union-attr]
