Claim HTLCs even if we're over our dust exposure if counterparty has reserve

[TheBlueMatt]

If we're close to our dust exposure limit and receive an HTLC which would put us over, we will fail that HTLC back, but there's no need to, if the counterparty has reserve greater than the dust exposure we should consider that sufficient.

[ariard]

Even if the counterparty’s reserve is more than our current holder dust exposure, we’re still exposed if the counterparty confirms a transaction where the dust outputs are committed as fees.

[TheBlueMatt]

Mmm, you're right as long as they force-close before they RAA our removal, but its really awkward that we fail to accept any HTLC in a specific range of values. Like, depending on your channel peer you may very well want to claim an HTLC rather than just blindly fail it back. I suppose that's maybe a good argument that the default dust exposure threshold should be something more like $50 rather than $5. Alternatively, if we moved to a dust-HTLC-count limit we'd kinda get that for free.

[TheBlueMatt]

We're gonna bump the dust threshold, and hopefully anchor-0-fee-HTLC-txn is good enough to deal with this.