Function build_transaction

Builds a transaction to send the given `amount` of satoshis to the destination address.

(
    ctx: &BitcoinContext,
    own_public_key: &PublicKey,
    own_address: &Address,
    own_utxos: &[Utxo],
    primary_output: &PrimaryOutput,
    fee_per_vbyte: MillisatoshiPerByte,
)