Fuzzy-match lines when applying edits from the assistant (#12056)

This uses Jaro-Winkler similarity for now, which seemed to produce
pretty good results in my tests. We can easily swap it with something
else if needed.

Release Notes:

- N/A

crates/assistant/Cargo.toml

@@ -40,6 +40,7 @@ serde.workspace = true
 serde_json.workspace = true
 settings.workspace = true
 smol.workspace = true
+strsim = "0.11"
 telemetry_events.workspace = true
 theme.workspace = true
 tiktoken-rs.workspace = true