Voting backend should provide vote count of ongoing elections

[finnbar]

To avoid worries about quorum, it would be useful for the voting backend to say how many votes an ongoing election currently has. You can currently check this in the database easily enough (and we have done so in the past for less important votes such as which charity to choose for Tabletop Radio) but it would be much more helpful for this information to be easily available to a voting admin.

From a moral standpoint this feels fine - the SU elections show % of voters / number of voters per society publicly, so us having access to this information feels fair.