Create a block that allows for entity autocomplete for switching communities

# Requirements #
- Make the experience as fast and easy for the user as possible

## Business Motivation ##
Reduce effort for users when finding community

## Acceptance Criteria ##
When I start typing into the field
Then the field will automatically make suggestions based on my input in real time
Given that I have supplied a value in the search box, I can submit via default drupal form submit (enter or clicking) and my community should update.