Publish twoliter to crates.io

[cbgbt]

While discussing support for twoliter on MacOS in #173, the idea to publish twoliter to crates.io was suggested.

We do own the package name, and publishing twoliter could make cargo install a pleasant mechanism for installing the twoliter binary.

On the other hand, there are many sub-crates of twoliter (pretty much anything under tools/ that I'd prefer not to support as generic libraries. We'll either need to find a way to keep these sub-crates "un-published" at the top-level namespace (which I don't believe is possible) or else ensure that the messaging on crates.io makes it clear that these sub-crates are implementation details of twoliter and not intended for general consumption.

Lastly, we should integrate some form of automated publication. There's a lot of positive feedback for release-plz as a possible solution there.