This allows us to 'nest' firmware formats, and removes a ton of duplication.
The aim here is to deprecate FuFirmwareImage -- it's almost always acting
as a 'child' FuFirmware instance, and even copies most of the vfuncs to allow
custom types. If I'm struggling to work out what should be a FuFirmware and
what should be a FuFirmwareImage then a plugin author has no hope.
For simple payloads we were adding bytes into an image and then the image into
a firmware. This gets really messy when most plugins are treating the FuFirmware
*as* the binary firmware file.
The GBytes saved in the FuFirmware would be considered the payload with the
aim of not using FuFirmwareImage in the single-image case.
Devices may want to support more than one protocol, and for some devices
(e.g. Unifying peripherals stuck in bootloader mode) you might not even be able
to query for the correct protocol anyway.
The end year is legally and functionally redundant, and more importantly causes
cherry-pick conflicts when trying to maintain old branches. Use git for history.
That giant uint64_t isn't looking so big now, and we'll want to add even more
to it in the future. Split out some private flags that are never useful to the
client, although the #defines will have to remain until we break API again.
