For now, a simple directory structure with filename based mapping is
used:
LOCALAPPDATA/cache/<main image id>/{<dll 1 image id>, <dll 2 image id>}
All cache blobs are loaded once at the start for simplicity, this will
also be useful in the future as metadata validation for settings etc can
be done just once.
and use it to commonise volatile metadata code (adding WOW64 image
voltmd support in the process). This will be extended to track mapped
images for code caching.