Option to filter choices

[xabbuh]

This is a global feature request replacing several more specific requests in the past. Basically the idea is to have a new choice_filter option that allows to filter the list of choices.

see #11847, #14072 for example

[ro0NL]

so we need a decision for #28624, which exactly implements this choice_filter 😅

i sense some skepticism to handle this in memory, compared to providing an optimized choice_loader. However for the "intl choice types" the choice_loader is predefined and hard to modify.

Also i'd argue one should ever pass a choice loader to the intl types, given those types should manage the data/choices for us. We only want want modify this list with filters and ordering.

[yceruto]

I think this choice_filter option makes sense only for intl types.

[fancyweb]

+1 to @yceruto. Having this filter option makes sense, but only on form types that you don't control and that force the choices. Adding it to ChoiceType would be contradictory since you already control the choices.