1a89d5230c examples: Add taproot-psbt workflow example (Duncan Dean)
Pull request description:
Will address #893.
Currently includes a BIP86 example (no spendable script path)
Working on script path and key path spending when both are possible spending paths.
ACKs for top commit:
tcharding:
ACK 1a89d5230c
apoelstra:
ACK 1a89d5230c
Tree-SHA512: 31d23914faedb2632d517f9a827075f1bf387df6d98f151000f70546d1e67ac332e698c6a01bda40a9baf5b25bff0114928edc0879c5e01753ecfc6ad182fe26