feat: transactions use transactions_sort_by

[reez]

Description

After discussing possible paths in #592 I believe the consensus was to just use transactions_sort_by under the hood in transactions because the example is likely what clients would expect out of the box.

Notes to the reviewers

I tested a local build of this in BDKSwiftExampleWallet to verify it worked as intended.

Changelog notice

Checklists

All Submissions:

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

New Features:

• I've added tests for the new feature
• I've added docs for the new feature

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

[reez]

Attempting to fix this failing CI on swift with #618

[reez]

Attempting to fix this failing CI on swift with #618

#618 fixed the failing CI, so this is ready to go (I rebased as well)-

[rustaceanrob]

ACK 16a6bc8

[thunderbiscuit]

ACK 16a6bc8.

[reez]

rebased, will merge after tests pass