Update examples

[rkalis]

• Fix bitbox import path
• Shorten bitbox import/initialisation
• Use the NETWORK parameter as an argument directly (rather than if-else)
• Replace some forloops with forEach
• Refactor OP_RETURN example to use async/await
• Fix linting issues
• Minor other changes

[cgcardona]

:tada: This PR is included in version 8.8.1 :tada:

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

Your semantic-release bot :package::rocket: