Action: Pick random user from channel

[I-Dont-Remember]

Choose a user from a channel at random to be used in other Workflow Steps.

Implementation Notes

Likely requires either a cache of users (DB work), or set a hard cap based on number of users we can draw from one or two requests to the Slack API.

They recommend no more than 200 results at a time , which handles a significant number of uses cases. What % of teams will be trying to use this on a channel with more than a couple hundred members? I'd hazard a guess at low%.

If we do a hard cap on size, then we are 1. won't have stale users 2. don't have to store anything. Win-win.

Existing examples

• Picker app
• https://github.com/m-vdb/slack-randompicker
• Less random, more fair, picker implementation

[I-Dont-Remember]

MVP implementation completed in #41.