Handle different action types for buttons

[wheresalice]

Following on from #2, we should handle the different button types differently. This will require backend changes whereas the initial grouping only requires frontend changes.

• Consent buttons related to a topic currently being discussed and may include counts for each.
• Requests are flags that appear, again with a count, and possibly anonymously.
• Responses are requests to speak and control your position in the stack of people wanting to speak.

Each of these should probably be a separate ticket, but this high-level ticket covers investigating and designing the architecture to support these requirements.