Sync with latest code on decidim-module-liquidvoting api client

[oliverbarnes]

The client on liquidvotingio/decidim-module-liquidvoting has diverged from the repo, and we should update the latter once the current round of changes is done.

And then package as a gem (#3)

[davefrey]

The latest client code in that repo also has some issues being tracked here liquidvotingio/decidim-module-liquidvoting#32. I propose we both resync the code and fix those things here in this repo, where we have spec support.

So the workflow might be like this:

1. copy their current work https://github.com/liquidvotingio/decidim-module-liquidvoting/blob/emulate-original-vote-button/lib/decidim/liquidvoting/client.rb back here as liquid_voting_api.rb
2. fix specs if needed
3. drive the work in Cleanup the api client Decidim::Liquidvoting::Client decidim-module-liquidvoting#32 here, using specs
4. copy the resulting liquid_voting_api.rb back to their repo as client.rb (or finish Package as a gem #3 and move that repo to use the gem instead of client.rb)

[davefrey]

This should include normalizing the return value for the four mutators, both in the graphql query and the return value from the api client, as is being done in liquidvoting/decidim-module-liquidvoting - api_client.rb