tree-wide: enable automatic growing of file systems in images in various tools...

tree-wide: enable automatic growing of file systems in images in various tools that deal with OS images

Let's enable this in all tools that intend to write to the OS images.
It's not conditionalized for now, as there already is conditionalization
in the existance or absence of the flag in the GPT partition table (and
it's opt-in), hence it should be OK to just enable this by default for
now if the flag is set.