Support for Bitcoin Descriptors

[deepsimulation]

There has been a rise in the adoption of Bitcoin descriptors across wallets. Bitcoin descriptors enable wallet interoperability amongst wallets that support scripts like multisig and miniscript. I'd love to see this package support descriptors in a minimalistic way. Some functionalities that will be useful include:

• Importing a descriptor and parsing it
• Generating addresses from descriptors
• Ability to sign transactions using descriptors

Thank you for considering this feature!

[paulmillr]

Seems reasonable. But it is very complex:

• there is even additional checksum
• not sure how well miniscript will work, it basically creates new script for which we need to craft logic for finalizing somehow
• there is a lot of hdkey stuff inside (and we don't even support hdkey for taproot yet)
• we can probably have something very basic (without miniscript), like mapping descriptors into payments

Example of complex descriptor

    Check("tr(a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd,{and_v(and_v(v:hash256(ae253ca2a54debcac7ecf414f6734f48c56421a08bb59182ff9f39a6fffdb588),v:pk(KykUPmR5967F4URzMUeCv9kNMU9CNRWycrPmx3ZvfkWoQLabbimL)),older(42)),multi_a(2,adf586a32ad4b0674a86022b000348b681b4c97a811f67eefe4a6e066e55080c,KztMyyi1pXUtuZfJSB7JzVdmJMAz7wfGVFoSRUR5CVZxXxULXuGR)})", "tr(a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd,{and_v(and_v(v:hash256(ae253ca2a54debcac7ecf414f6734f48c56421a08bb59182ff9f39a6fffdb588),v:pk(1c9bc926084382e76da33b5a52d17b1fa153c072aae5fb5228ecc2ccf89d79d5)),older(42)),multi_a(2,adf586a32ad4b0674a86022b000348b681b4c97a811f67eefe4a6e066e55080c,14fa4ad085cdee1e2fc73d491b36a96c192382b1d9a21108eb3533f630364f9f)})", "tr(a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd,{and_v(and_v(v:hash256(ae253ca2a54debcac7ecf414f6734f48c56421a08bb59182ff9f39a6fffdb588),v:pk(1c9bc926084382e76da33b5a52d17b1fa153c072aae5fb5228ecc2ccf89d79d5)),older(42)),multi_a(2,adf586a32ad4b0674a86022b000348b681b4c97a811f67eefe4a6e066e55080c,14fa4ad085cdee1e2fc73d491b36a96c192382b1d9a21108eb3533f630364f9f)})", MISSING_PRIVKEYS | XONLY_KEYS | SIGNABLE, {{"51209a3d79db56fbe3ba4d905d827b62e1ed31cd6df1198b8c759d589c0f4efc27bd"}}, OutputType::BECH32M, /*op_desc_id=*/{}, {{}}, /*spender_nlocktime=*/0, /*spender_nsequence=*/42, /*preimages=*/{{ParseHex("ae253ca2a54debcac7ecf414f6734f48c56421a08bb59182ff9f39a6fffdb588"), ParseHex("000000000019d6689c085ae165831e934ff763ae46a2a6c172b3f1b60a8ce26f")}});