This refactoring of the chip specific bootloader creates the internal boot instance and aligned
buffer in the prepare stage, so that they are automatically dropped after. This unlocks a use
case where peripherals owning the flash need to be Drop'ed before load() happens.
* Allow manipulating state without accessing DFU partition.
* Provide aligned buffer when creating updater to reduce potential wrong parameters passed.
It seems as if the arm compiler can does not care about whether the bootloader symbols are undefined if the default() function is never used. The x64 compiler does care however, so this change ensures that we can instantiate the types from tests.
