Add miniscript script cmd

[louisinger]

This PR adds a new miniscript subcommand. script lets to convert a miniscript policy into bitcoin script.

for instance:

> hal miniscript script "and(pk(025625f41e4a065efc06d5019cbbd56fe8c07595af1231e7cbc03fafb87ebb71ec),pk(025625f41e4a065efc06d5019cbbd56fe8c07595af1231e7cbc03fafb87ebb71ec))"

{
  "hex": "205625f41e4a065efc06d5019cbbd56fe8c07595af1231e7cbc03fafb87ebb71ecad205625f41e4a065efc06d5019cbbd56fe8c07595af1231e7cbc03fafb87ebb71ecac",
  "asm": "Script(OP_PUSHBYTES_32 5625f41e4a065efc06d5019cbbd56fe8c07595af1231e7cbc03fafb87ebb71ec OP_CHECKSIGVERIFY OP_PUSHBYTES_32 5625f41e4a065efc06d5019cbbd56fe8c07595af1231e7cbc03fafb87ebb71ec OP_CHECKSIG)"
}