[Dev] Integrate improvements for our EnumSetProperty type

[ljacqu]

We want to have a ConfigMe property of Set<E> type where E extends Enum<E>, but we cannot do so elegantly because of a few ConfigMe bugs:

• exporting as Set results in ugly structure YamlFileResource should export Set as a yaml list ConfigMe#27
• enums are exported prefixed with the qualified class
• field with child property type is ignored by ConfigMe Declaring a field as a child class of Property will make it be ignored ConfigMe#28
  • I expect that we can switch back to having Property<Set<E>> once this story is fully done, but in the meantime if this is solved and we can avoid the casting, this is already a good improvement

Integrate the fixes once they're available or find viable workarounds. Search the code for TODO comments with this issue number.