Prevent fundee from force closing zero-conf channel before confirmation

[Crypt-iQ]

If the funding tx hasn't been confirmed and isn't in the fundee's mempool, the fundee's contractcourt will advance to StateContractClosed without broadcasting the unilateral close (since it would be rejected). The funder will be unaware the fundee is trying to close the channel and will still think it's open. The solution is to probably disallow the fundee from force closing the channel before a single confirmation. The same thing could be done for coop closing.

[alexbosworth]

It could be nice if the channel can just go into limbo on both sides rather than force close, similar to what happens if the cooperative close fee negotiations fail