Add explicit "no inbound channels accepted" flag in config

[TheBlueMatt]

Users can currently approximate "I refuse all inbound channels" by doing something like setting ChannelHandshakeLimits::min_funding_satoshis in UserConfig::peer_channel_config_limits to something greater than 21 million BTC, but ideally we'd just have a simpler flag users can set instead.

Note that users today can always change their default-inbound config by setting ChannelManagerReadArgs::default_config to anything they want.

[TheBlueMatt]

On second thought, when we do this, we should just have a setting to kick the decision out via an event. That would give the user some kind of "someone is asking to open a channel, peer id is X, value is Y" event and then let users either say yes or no.

[tnull]

The config option to disallow incoming channels should be addressed by #1173.

Regarding the second part, i.e., yielding an event and awaiting user input, I'm not yet entirely sure where/how long to store the pending inbound OpenChannel messages and how to handle them, for example, if the user does not react at all/in time. This could require some logic akin to c-lightning's hooks. However, the question then is whether introducing this kind of complexity is warranted given the use case?

[vincenzopalazzo]

This was fixed by https://github.com/lightningdevkit/rust-lightning/pull/1173/files?

[TheBlueMatt]

Yes, the immediate issue here was fixed. I've moved the "part 2" to #1242.