[FEATURE] Add default value for sequence in Transaction

[swierzbicki]

Summary

Currently when we built and input for new transaction:

    const input = {
        sourceTransaction,
        sourceOutputIndex: 0,
        unlockingScriptTemplate: new P2PKH().unlock(privKey),
        sequence: 0xffffffff
    }

We need to always give a sequence value. As far as i know. In the most of the cases it will be a one, fixed value 0xffffffff.

Motivation

It would be easier to use ts-sdk for someone who just starts the journey with the ts-sdk/bsv.