Removal of abi_json_to_bin and abi_bin_to_json

[ryucrypt]

As seen in the following 2 commits:

• eos-amsterdam-rnd/wax-leap@d680c62
• eos-amsterdam-rnd/wax-leap@7baee72

The removal of these endpoints are now merged in, already inaccessible for BPs which upgraded to v4.0.4, effectively breaking most Python libraries which utilises them to interact with Antelope. Since pyntelope does not rely on these endpoints, it is still working.

However, the currently implemented types are limited (e.g. missing extended_asset and custom types). Just wondering if implementation of custom types by fetching ABIs are planned (e.g. https://github.com/EOSIO/eosjs/blob/40a7600b2f53f9512c886e032dc46e1232ccca4f/src/eosjs-serialize.ts#L1390 new_type_name, variants)?