For older lightningd, we copy field into the raw dict, for newer we recreate the old
"payload" member.
We do fix up the custom_notification test which set params to a string instead of a dict:
that's just weird!
We also change the hacky parsing to proper dict extraction.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Changelog-Changed: pyln-client: plugin notifications parameters now exposed directly, not wrapped in `params` object.
fc5edea999