[Feature request] Add channel expire time

[Darth-Coin]

Description

Yes, we all want to have inbound LN channels open until the end of times.
But we should also be aware that who is open a channel towards our node is practically putting his own money into that channel.
So I suggest to be added a feature of "time to expire the channel". A limited time that the channel could be dormant (no activity).

Solution proposal

• inform the user when is opening the Dunder channel about the time limit for dormant channels.
• if the channel have activity will not be closed
• if the channel have most of the liquidity on the Dunder side (let's say 90%) for a long period (Dunder operator could decide that in his settings), then the channel get closed.

Not sure if this can be achievable in a programmable way, but it can be started with some simple alerts, for the Dunder operator and for the user.