Issue #3544218: Add static OTP configuration for automated testing
- Added optional 'static_otp_code' field in dev mode settings
- When dev mode is enabled and static OTP is set, uses the fixed code
- When empty, generates random codes as usual
- Works with both 'Globally enabled' and 'Users optionally' pathways
- Added hook_update_8006 to add the new config field
- Field only appears when dev mode is enabled for clarity
Closes #3544218