Observers are no longer able to interact with Power-Ups

Issue Summary

Observers are unable to interact with Power-ups when viewing a board.

Steps to Reproduce

1. Add an observer to a board: https://support.atlassian.com/trello/docs/adding-observers-to-boards/
2. Access the board from the observer's account
3. Attempt to make use of some Power-ups - For example Calendar Power-up

Expected Results

Users should be able to interact with the Calendar Power-up through the button at the top of the board.

Actual Results

Board does not show calendar Power-up button.

Workaround

Currently there is no known workaround for this behavior. A workaround will be added here when available