Surprisingly easy to do. Almost all of the diff resolution was mechanically
* replacing boost::variant with std::variant
* replacing Optional with std::optional
* then replacing `nullopt` with `std::nullopt`
* updating the RPC functions for the new RPCArg::Default type
* update the tests/ directory to make new (since 22) tests use arrays for
createrawtransaction outputs
* other ad-hoc changes to function parameters etc (not too many of these)
I had to "really" change the code in PrecomputePSBTData, which was introduced
in 22.0 and affected by PSET, but this function was like 8 lines long so it
was easy.
Reviewing the diff may be a bit difficult because of the mix of mechanical
changes and ad-hoc things. Probably the most straightforward thing to do
is to redo the merge, `sed -i` to fix the boost::variant and Optional stuff,
then diff the remaining conflicts against this commit.
TODO: grep for `blindpsbt` and you will see that this RPC is still referenced
in documentation and help text even though it was deleted. Need to fix this
in 0.21 in a separate PR.
