Make CarStatusBar a Singleton

NPE was caused when we were pointing to a seprate instance of
CarStatusBar where mBiometricUnlockController was null.

Bug: 143239523
Test: Manual -- First, flash the master branch on Hawk. Second, exit
the Quick Settings page. Third, reboot Hawk and verify that it does not
crash.

Change-Id: Ic24eed1759dfaa7072a41d5fd7364c3cee71851b