refactor: Move cleaning/validation functions from SiloQueryModel further up the call stack, into the controllers.

[fhennig]

In SiloQueryModel there is the getGenomicSequences function which uses two functions (mapSequenceNames, mapSequenceOrderByFields) to clean up/change cases of user input.

I think we should move these closer to the API endpoints.

For OrderByFields we actually have the OrderByFieldConverter which is used for get requests. It also does cleaning internally, but just for regular fields. There is actually this line:

fun clean(fieldName: String): String = caseInsensitiveFieldsCleaner.clean(fieldName) ?: fieldName

which is also not so elegant, because we're cleaning a few fields, but then if we don't know the field, we just pass it through. Apparently, in the passed-through fields could be sequence names. It would be good to instead move the logic from mapSequenceOrderByFields here (if possible), so it's all in one space. And we could actually reject user input that is neither a field, nor a sequence name.

For mapSequenceNames, this is also quite similar to the way we check for order by fields. Instead of a List<String> we could use a List<Gene> and use a Converter that validates the given gene input already at the API endpoint level.