Updated all ButtonGroups and MultiButtonGroups to mirror changes in react-components

Summary: react-components now refers to the contents of a button as `content` rather than `text.
In addition, there's a new react-component for multi-button groups that replaces our existing
component in /components.

Test Plan:
- Try interactive-graph.
- Try numeric-input.
- Try grapher.
- In each case, verify that the button groups work as before!

Auditors: jack

Subscribers: joel