find_votes and list_votes fixes

SQL function get_account renamed find_account_id to follow naming scheme.

Vote related views/types/functions extended by id since database_api requires it.

New SQL function to cover find_votes functionality.

[Fix]: Neither voter nor post is mandatory in list_votes calls.

[Fix]: fixed internal _get_post_id in bridge_api

find_votes_impl no longer requires full context, just what it actually uses: db; it also no longer checks passed arguments, only its official API version does.

list_votes_impl removed since only its official version is needed

[Fix]: Official API find_votes/list_votes now properly pack response in dictionary with 'votes' list