Unified Snap

[snadrus]

This addition to the fast snap mainline modifies supraseal:

• No more objcopy: An interface glues the filereader with the NVMe driver.
• Faster build using parallelism
• AMD64v3 becomes the default, as Curio has had for a while (2013-2015 era introduction).
• Added a fallback for CPUs without SHA-NI (v3 but not v4) to be able to use Supraseal.

This should make fastsnap the only path needed for Curio.

Todo: unify make batch/curio, healthy path for old linuxes