Use proper yaml for the mongod config

[h-haaks]

[h-haaks]

@stevenpost This is just a start with 'systemLog' Easy to extend to the rest of the config including a merge of @config_data

[h-haaks]

I do think this is the right way to move this. As we already have a major release going anyways I think we should consider renaming some params and removing seldomly used ones. I also think expected parameter values should align with https://www.mongodb.com/docs/manual/reference/configuration-options/ and not mongo/mongosh options.

[h-haaks]

Cleaning up the params of mongodb::server should be done in a separate PR btw.

[h-haaks]

Requires #741 before converting net. settings to pure yaml.

[stevenpost]

I restored my branch so you can take what you find useful. I think using YAML.safe_load is better suited in unit tests when compared to regexes.