[BB-3704] Separate ThemeColor Component

Created by: arjunsinghy96

Extracts the color pickers to a separate component.

JIRA Tickets BB-3704

Testing Instructions

1. Checkout to this branch
2. Start OCIM backend in vagrant using make run.dev
3. Start frontend using npm run start --prefix=frontend
4. Make sure you have a BetaTestApplication with a test user already created. If not visit admin and create appropriate records. Without these the Frontend will not be fully functional.
5. Visit http://localhost:3000/console/theming/preview-and-colors
6. In react devtools, check that ThemeColor component is used to display the color components
7. Update color values and check Preview is updated.
8. Check in django admin that theming changes are reflected in the BetaTestApplication