Advanced query input: add `?` button that opens an info box to explain what you should type there

[fengelniederhammer]

Currently, users probably won't understand what they should type into the advanced query box to get a valid query.

[fhennig]

IMO it'd be more sensible to move the component into dashboard-components where we already have reusable components for the helper button. Otherwise we'd start duplicating - I don't think that's sensible.

Agree? If so, we'd block this issue.

[fhennig]

Should we try and link to the underlying LAPIS docs? Or should we write our own text? (Some docs for context: https://lapis.cov-spectrum.org/open/v2/docs/concepts/advanced-query)