New API Endpoint for Account Proxies

In alignment with request block_explorer_ui#426 (closed) , we would like to create a new endpoint that allows fetching, for a specified account, a list of all accounts who have set this account as proxy, alongside other useful details such as proxy date and proxied amount.

Candidate table to fetch the data per discussion with @mzander is current_account_proxies

For testing purposes, this call is available in hived to find proxy accounts.

curl -s --data '{"jsonrpc":"2.0", "method":"database_api.list_accounts", "params": {"start":["gtg"], "limit":10, "order":"by_proxy"}, "id":1}' https://api.hive.blog