Enable `clippy::unwrap_used` to better handle panics

[nyurik]

I think these restrictions should improve our code quality - i.e. we shouldn't panic (unless its a test). To enable, modify root Cargo.toml and add these lines, and just clippy it...

 [workspace.lints.clippy]
 # Restrictions
 panic_in_result_fn = "warn"
 todo = "warn"
+unwrap_used = "warn"
 # Pedantics without being too noisy
 pedantic = { level = "warn", priority = -1 }