Plugin event notification subscription wildcard support

[rustyrussell]

Subscribing to "" will now give you every event: I've added support to pyln-client and libplugin for this.

Note: you can tell which notification it was in Python by having an argument called "request" and looking at "request.method"

Suggested-by: @ShahanaFarooqui

[ShahanaFarooqui]

Related Issue: #6340
Related PR: #6345

[ShahanaFarooqui]

@rustyrussell It throws error ValueError: No subscription for warning found., when I subscribed for all events with "".
Eg.

@plugin.subscribe("")
def subscription_handler(plugin, response, **kwargs):
    plugin.log("Hello")

[rustyrussell]

Hmm, that will happen if you're not running the modified pyln-client? Make sure you're running under poetry shell, and maybe poetry install?

[ShahanaFarooqui]

It is now working as expected. Good to go.

[ShahanaFarooqui]

I would recommend switching the wildcard from an empty string to [""] format. This format aligns with common practice of using "" as a wildcard symbol and array will be helpful in future with selective subscriptions.

[rustyrussell]

I have switched to * everywhere, testing now.

Complete!

[rustyrussell]

Fixed up now notifications are object-wrapped in master.

[ShahanaFarooqui]

Ack c76b9d9