In further preparation for the auth and cert queries being handled
as special contents from `about:` this excises the query pathway
from the llcache pretty much entirely.
Signed-off-by: Daniel Silverstone <dsilvers@digital-scurf.org>
This reworks CONTENT_MSG_ERROR to be structured data and
removes the CONTENT_MSG_ERRORCODE message kind.
Signed-off-by: Daniel Silverstone <dsilvers@digital-scurf.org>