Add user defined script as part of multisig

[topologoanatom]

Changes

Redesigns P2TR flow to hold 2-of-2 multisig from previous versions and user defined recovery path as leafs of taptree (key path unspendable); removes p2sh, p2wsh types.

• implement logic and update demo for bitcoin regtest;
• implement logic and update demo for elements;

[topologoanatom]

It's tricky to finalize generic user's script, so finalization is handled only for multisignature path. CLI provides tooling for manual finalization of CSV script for demo purposes.

[ivanlele]

Also, we've added CI in development, can you rebase from it? I see one merge conflict