Adding testing for optimized flash super

Adding test cases for correct formation of optimized flash super task.
We are adding an explicit pattern match for this task to be correctly
formed. Changing Optimized flash task to only remove the reboot to
userspace as a user might want to reboot back to bootloader after
flashing. We also need to change a couple functions to take a
IFastbootDriver to mock up the initialization path.

Test: fastboot_test
Bug: 297085098
Change-Id: Ic5c63bd4057ca6d64647134e5ce33fef12077fdb