set_proposed_producers_ex (WTMSig Block Signing) Support

[b1bart]

Change Description

This PR adds support for the set_proposed_producers_ex intrinsic enabled by the WTMSig consensus upgrade to EOSIO: EOSIO/eos#7404

This also fixes attempts to fix an ABI generation issue with variants where certain types were not getting included in the resulting ABI during ABI generation

API Changes

• API Changes

A new overload is presented for set_proposed_producers which takes a new data structure producer_authority. This data structure represents a Weighted-Threshold Multi-Signature block signing authority which is a superset of what was expressible with a producer_key. The original data structure and function signature remain valid so, this should be a backwards-compatible change for any existing use cases.

new method:

in eosio/privileged.hpp

std::optional<uint64_t> set_proposed_producers( const std::vector<producer_authority>& prods);

Documentation Additions

• Documentation Additions

See comment strings on new methods and data structures.