RBF follow-ups

[darosior]

Here are a couple things which didn't warrant holding up the PR but would be nice to have:

• Expand the explicit-RBF-signaling sanity check to all conflicting transactions (commands: add rbfpsbt command #816 (comment))

• The "feerate too low" error could include the minimum feerate to be more helpful (commands: add rbfpsbt command #816 (comment))

Added after @jp1ac4 comments:

• We can also check if any directly conflicting transactions are spending unconfirmed change and include these unconfirmed coins as candidates for the replacement transaction (Let coin selection use (some?) unconfirmed coins #826 (comment)).
• We should add ancestor info to coin selection candidates when creating a replacement to ensure we pay extra for any parent transactions that have a lower feerate (commands: include unconfirmed change as coin selection candidates #873 (comment)).
• We should support RBF on a recovery transaction. Currently, the RBF candidate coins all have their sequence set to None.

@jp1ac4 feel free to suggest more.

[jp1ac4]

We can also check if any directly conflicting transactions are spending unconfirmed change and include these unconfirmed coins as candidates for the replacement transaction (#826 (comment)).

[jp1ac4]

We should add ancestor info to coin selection candidates when creating a replacement to ensure we pay extra for any parent transactions that have a lower feerate (#873 (comment)).

[jp1ac4]

We should support RBF on a recovery transaction. Currently, the RBF candidate coins all have their sequence set to None.

[aaroncarlucci]

Tried to address the second bullet in the description with #1186.

[nondiremanuel]

I updated the issue description to include Michael's comments. I also divided it in different tasks and marked the second one as completed as per @aaroncarlucci's PR #1186 which was merged (thanks!)

[jp1ac4]

We should add ancestor info to coin selection candidates when creating a replacement to ensure we pay extra for any parent transactions that have a lower feerate (#873 (comment)).

See #1255.