This commit switches UID hashing from md5 to a highway hash. It also
moves the salt value out of the file plugin - and makes it
installation-specific instead - it is moved to the global namespace.
There now are digest hash functions to make "static"
installation-specific hashes that are stable over workers available to
everyone; hashes can be 64, 128 or 256 bits in size.
Due to the fact that we switch the file hashing algorithm, all file
hashes change.
The underlyigng algorithm that is used for hashing is highwayhash-128,
which is significantly faster than md5.
This allows one to tune the number of protocol violations to tolerate
from any given analyzer type before just disabling a given instance
of it.
Also removes the "disabled_aids" field from the DPD::Info record
since it serves no purpose: in this case, calling disable_analyzer
multiple times for the same analyzer is a no-op.
