Added Flashing Plan

Fastboot has a lot of flags that are used by many different functions
including the Flashall Class and newly added FlashSuperTask. Passing all
of these flags as paramaters is cumbersome, so adding a Flashing Plan
that contains these flags simplifies the code.

Test: tested Flashall and update img.zip on raven
Change-Id: I9c842f25389a20b852d55f684e1b86040af1d86a
Bug: 194686221