Add FieldType setting to set minimum/maximum amount of CVLs

When you sell clothes online you need at minimum 5 care icons (Washing instructions) to be legally compliant, we have solved this by using a CVL, but we have no way of enforcing 5 selected values without a server extension.

A setting on FieldType to set a minimum or maximum amount CVL values would give us the functionality we need.

We tried with a regex but it did not work.