[Rooming] Multiple contexts for rooming

[leowilkin]

Attend should support pre, and post event rooming being separate lists, and having a select list of attendees that are roomed in a hotel, instead of assigning everyone a room.

[leowilkin]

Let's also work on integrating this into the onboarding process: https://build.fillout.com/editor/tmL3PWkb1Aus/edit#