At the moment FuChunks are sometimes mutable, and sometimes immutable, and it's
all a bit too low level for comfort.
Before we can do any kind of optimisation or verification we need plugins to
stop reading directly from the C structure. The aim here is to make FuChunk
optionally mutable without making assumptions about the memory model, and also
to be able to introspect it for the docs.
Asking the user for the UID mapping isn't working very well, as it requires lots
of manual handholding. It also doesn't work very well when the device vendor
does not actually have a PCI ID or if the vendor has split into two entities.
Just use the OUI address as an additional VendorID and match any of the device
IDs against any of the metadata-supplied values.
