[Plan Visualization] Overhaul tree visualization protocol

[clarkzinzow]

The current TreeDisplay + multiline_display visualization protocol for logical/physical plans does not provide enough display flexibility for logical/physical ops with nested structures and/or long descriptions.

We should refactor this to use a protocol that:

1. Allows ops and contained structures to expose nesting depth to display consumers.
2. Eliminates most boilerplate by leveraging a sensible trait + a derive macro.
3. Allows ops and contained structures to expose summary information in case a particular line ends up being too long.