New config parser

[prandla]

I wrote a custom parser that turns the output from tomllib into a strongly-typed dataclass-based config object. (This is basically the same as what pydantic does, but it's much smaller. We really don't need to bring in such a big dependency for this, as was pointed out by Martin.)

I also reorganized the config file format into sections, which are used in both CMS code and in the config file. This means the PR is quite huge though... The main things to review are the .sample.toml files, cms/conf.py, and cmscommon/conf_parser.py.

I also:

• added all undocumented options into cms.sample.toml and cms_ranking.sample.toml
• removed other_services from the config and replaced core_services with just services
• removed the deprecated is_proxy_used option. People need to port their configs anyways, so they can replace the deprecated option with the new one.
• removed the undocumented and unused timeout parameter from the RWS config.
• removed the ability to set web_dir in RWS config. I can't see any reason why anyone would need to change that.

This is an even more substantial change than the json->toml one. I'd like to get this in before we release 1.6, to avoid people having to port their configs twice (or well, the ones who were using the git version need to do it twice anyways, but that's unavoidable).

Maybe we should also provide a script that auto-converts json to the new config format.

[veluca93]

(but please don't merge until end of IOI ;-))