### What problem does this PR solve?
Update for Admin UI:
- Update file picker input in **Registration whitelist** > **Import from
Excel** modal
- Modify DOM structure of **Sandbox Settings** and move several
hardcoded texts into translation files
### Type of change
- [x] Refactoring
### What problem does this PR solve?
Add whitelist management and role management in Admin UI
### Type of change
- [x] New Feature (non-breaking change which adds functionality)
