Java typed-decoders features

[S11001001]

There is now a collection of associated ledger client facade issues, all somewhat loosely dependent on #14313 (though truly only interface FromValue is required for all of them).

• [ ] on the querying side, ACS and transaction streams: #14969 needs very little of decoders for templates, since TemplateCompanion already carries decoders. It's a little trickier, but interface views can also be incorporated by adding interface views to InterfaceCompanion
• [ ] on the choice metaprogramming side, there is #14329. The basics can be done without decoders, but full support for decoding choice arguments and return types needs them
• [ ] ChoiceMetadata may also be a good basis for #14312. However, we have to seriously discuss what we want to break with that change
• [ ] #13768 does not need anything from value decoders.
  • [ ] However, we can use this for the very similar #12897. We don't need to generate any code for #12897, since it can be derived from the values introduced in #13768 if we also have #14329
    • [ ] this would also close #14421