maintain more AST info when formatting a RHS

[calebcartwright]

We currently utilize generics, primarily bound on our Rewrite trait, when formatting a RHS (e.g. on an assignment) which makes perfect sense given the high number of expression variants, bounds, etc. that can be encountered. However, in doing so the functions that actually define the logic which handles orchestrating the rewriting of the RHS and then combining it with the LHS are missing various data points from the respective AST nodes.

That's not been a problem historically, however, we have a few outstanding requests for more optionality around formatting of chains including formatting results which knowingly exceed the max_width boundary. In order to support these use cases while still being able to block indent the start of the RHS some additional AST metadata will be needed, and that metadata is accordingly incorporated and passed along with the changes in this PR.

Refs #3863 #4306