[LinearMessageView::Iterator]: decrement feature request

[kevinchristensen1]

Feature Request: Extend LinearMessageView::Iterator to have a decrement function for the ability to scrub through data without needing to cache externally
Example Use Case: A large mcap file has hundreds of thousands of image/data pairs, and an application would like to be able to scrub forwards and backwards in time to inspect.

If there is an easy way to achieve the same functionality currently, would it be possible to provide an example?
Thanks!