Have some stricter parsing of the dolos.toml config

[mpizenberg]

Currently the parsing of the config file dolos.toml is rather permissive and doesn’t prevent or warn in the case of unknown fields, or rather misplaced fields. It got me into trouble because I had manually written:

[serve]
listen_path = "dolos.socket"
magic = 764824073

Instead of [serve.ouroboros] for the section title. This lead to an unrelated error message about the database when running dolos serve.

It would be very nice if those kind of mistakes where caught at parsing time.