Fix TxOrdering::Shuffle to also shuffle the inputs

[notmandatory]

Description

Fixes #865

This is a small change to make it so that TxOrdering:Shuffle also shuffles the inputs.

Notes to the reviewers

It looks like input shuffling was meant to be excluded in #38 when the TxOrdering::Shuffle option was added since the corresponding test check that inputs are not shuffled.

Changelog notice

Fixed

• The TxOrdering::Shuffle option in the TxBuilder now also shuffles the inputs.

Checklists

All Submissions:

• I've signed all my commits
• I followed the contribution guidelines
• I ran cargo fmt and cargo clippy before committing

Bugfixes:

• This pull request breaks the existing API
• I've added tests to reproduce the issue which are now passing
• I'm linking the issue being fixed by this PR

[notmandatory]

@afilini I'm a little worried that you intended to not shuffle inputs since your test verifies they're not shuffled. Do you remember is there's any reason not to shuffle the inputs?

[notmandatory]

This doesn't seem like a critical issue so I'll re-do it for a future 1.0.0 alpha release after #793 is merged.

[notmandatory]

Already fixed!