We've had recurring issues with `println` calls sneaking in
where `log` crate macros would be more appropriate.
This commit adds a Clippy warning for uses of the global I/O macros,
i.e. `print`, `println`, `eprint`, `eprintln` and `dbg`.
The lint is disabled by a more-specific `clippy.toml` in the `cli` and `sqltest` crates,
as well as using `allow` attributes in `standalone`'s `subscommands` module.
Additionally, this commit converts a handful of prints in `core/utils` to `log::info`.
Phoebe Goldman