Add test vectors for option_anchors_zero_fee_htlc_tx

[wpaulino]

While working on the integration of option_anchors_zero_fee_htlc_tx for rust-lightning, I noticed that the test vectors were only for the original option_anchors commitment format, which is also the case for BOLT-3.

These are the same test vectors as those found under Appendix F, except that each HTLC has a zero fee transaction instead, resulting in a signature change.

[t-bast]

ACK https://github.com/lightning/bolts/pull/1018/commits/bcd452e06a9a5a51b9f7eabd8392a4ed0ebb1fac, eclair agrees with those test vectors. Just need to fix the markdown link and we should be good to go.

[wpaulino]

Nice catch! Confirmed rust-lightning matches these now.

[t-bast]

ACK https://github.com/lightning/bolts/pull/1018/commits/77eca9c7267794bdafe72e107cbc1c9d1dc3e2a1, eclair works fine with the latest changes, thanks @wpaulino and @ellemouton!