[keepstore] optimize md5sum calculations
There is now a Go package to speed up md5sum calculations when the hardware supports it (AVX/AVX2 extensions, which are common):
which is described here:
Keepstore should leverage this library to speed up its hashing, if the hardware it runs on supports the necessary extensions.
Ideally, this goes into our codebase in a such a way that all our Go code that calculates md5sums leverages it automatically.