Switch from a string core to a 128-bit integral core. This should make
Fingerprints much cheaper to copy around and sets us up for a future
where we can provide alternative implementations of the ambient hashing
algorithm.
rdar://72313506
Take advantage of the binary swiftdeps serialization utliities built during #32131. Add a new optional information block to swiftdeps files. For now, don't actually serialize swiftdeps information.
Frontends will use this information to determine whether to write incremental dependencies across modules into their swiftdeps files. We will then teach the driver to deserialize the data from this section and integrate it into its incremental decision making.
