Configurable UniqueBy

[whittlbc]

We need to make it possible for users to configure a custom "uniqueBy" mapping between a live object and their custom live table.

Useful component links:

• https://github.com/spec-dev/app/blob/master/src/components/shared/panels/EditableLiveColumns.js
• https://github.com/spec-dev/app/blob/master/src/components/shared/panels/EditColumnPanel.js