July merge remaining tasks

[phillco]

• Need to reconnect the file watcher on editors state to update the visible ranges (not a huge deal, just means hats don't update when you resize the window)
• Clients need to make sure they're using line/column for hats (got rid of offsets)
• Testing

Medium priority

• Clients need a good way to switch back and forth between the old sidecar and the new one until we're confident it's stable