Fix Folding Ranges

[ChrisPenner]

Overview

Quick one to upgrades the folding ranges feature to use the new binding-level span annotation which are more accurate.
Old folding ranges would sometimes fold awkwardly in the middle of type-annotations or below the actual start of bindings/watches

Implementation notes

• Swap existing folding ranges to use the new top-level spans.
• Adds a debug.folding-ranges helper which annotates the source annotations from the last parsed file.

Test coverage

Also adds debug.folding-ranges ucm command and transcripts which use it.