Added anchor support to commitment HTLC outputs

[ksedgwic]

Still needed:

• rebase onto upstream (requires updating r-l-s)

[ksedgwic]

I can't reconcile the WEIGHT_{OFFERED,RECEIVED}_HTLC calculations at
https://github.com/lightning-signer/rust-lightning/blob/master/lightning/src/chain/package.rs#L48
with
https://github.com/lightning/bolts/blob/master/03-transactions.md#expected-weight-of-htlc-timeout-and-htlc-success-transactions

rust-lightning sez 139 and 133 and the BOLT specs 140 and 133 (w/o anchors)

I wanted to understand this before adding the anchors weight estimates ...