Summary

#4149
This PR tries to fix several issues when we format a node with a range.

1. The transform function builds the source map by iterating over all tokens and pushing source text in the builder. This correctly builds up the source text for the sub-tree, but the offsets are incorrect if the root isn't at the start of the document.
2. The transform function can detach a node if it updates a tree (splice_slots) while a traversing. We must return transformed a node back into the original tree to correct offset and sometimes a formatting result depends on a parent kind.

Test Plan

cargo test

Documentation

• The PR requires documentation
• I will create a new PR to update the documentation