Add design debugger

[tylers-username]

Changes Summary

• Adds theme/debug components: DesignDebugger and Draggable
• Adds theme/debug unit tests: DesignDebugger Test and Draggable Test
• Adds DesignDebugger to App.tsx
• DesignDebugger conditionally renders based on REACT_APP_ENABLE_DESIGN_DEBUG being set

Test Changes

1. npm install from repo root
2. Test without design debugger: npm run start from repo root
3. Test with design debugger: REACT_APP_ENABLE_DESIGN_DEBUG=1 npm run start from repo root
   • Any "truthy" value on REACT_APP_ENABLE_DESIGN_DEBUG should make the debugger appear