Initializing cargo-maelstrom.toml

If there is no cargo-maelstrom.toml in the workspace root, then cargo-maelstrom will use a default configuration.

When it comes time to build a more complex configuration, you can have cargo-maelstrom write out the default configuration:

cargo maelstrom --init

This will create a cargo-maelstrom.toml file in the workspace root, unless one already exists, then exit. The resulting cargo-maelstrom.toml will contain the default configuration. It will also include some commented-out examples that may be useful.