CLI to add a proto file to config

[preiter93]

Add a 'wireman add file.proto' command line functionality which automatically adds file.proto and the path to the wireman.toml config.

• Parse includes and files from current config.
• Check if any path or subpath matches the path to file.proto.
• Check if file.proto already exists in the config.
• Figure out how to best add the file, i.e. which part of the path should be added to includes and what to files.

Adding values to a toml while preserving the original file can be achieved with the toml-edit crate. See https://github.com/toml-rs/toml/blob/main/crates/toml_edit/tests/testsuite/edit.rs#L588