Try to remove SearchContext usages on the SearchInputTransformer hierarchy

The SearchInputTransformer interface has three methods receiving a SearchContext:

• void validateParams(User user, SearchContext searchContext, FieldValuesHolder fieldValuesHolder, I18nHelper i18nHelper, ErrorCollection errors);
• void populateFromQuery(User user, FieldValuesHolder fieldValuesHolder, Query query, final SearchContext searchContext);
• boolean doRelevantClausesFitFilterForm(User user, Query query, SearchContext searchContext);

That interface is being implemented by ~30 classes, and only a few of them are actually using the SearchContext on those methods.

We need to investigate if those usages are actually needed or if we can get rid of the SearchContext in this whole hierarchy.

The classes that we need to further investigate are CascadingSelectCustomFieldSearchInputTransformer, SelectCustomFieldSearchInputTransformer and AbstractCustomFieldSearchInputTransformer.

For the implementations of those methods on those classes it is not very obvious if the usages of the SearchContext are really needed (from an behavioural point of view)