feat(svm): initial sbfv2 work

[Rexicon226]

This PR has two main improvements.

The first is including a source for building the testing ELF binaries from scratch, using Zig. The method there is quite simple, we emit LLVM bitcode (not IR, since IR is not backward compatible), and use the SBPF LLVM fork to compile and link to a shared library. There are certain ELF binaries that we want to be compiled for SBPFv1 as well since they test features that have been changed or deprecated since, so those are in the V1_FILES array in the bash script.

The second major change is expanding the ELF parser to support parsing SBPFv2 binaries. There isn't too much to say there, my implementation just closely follows how RBPF and Firedancer parse their ELF binaries. The tests should ensure that it's parsing correctly, as well as my solana-conformance work with the elf parser shows that most inputs pass.

[Rexicon226]

• chore(svm): adjust sbpf version naming #507
• feat(svm): PQR support #501
• feat(svm): initial sbfv2 work #496 👈 (View in Graphite)
• main

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[yewman]

couple of minor questions otherwise lgtm

[dnut]

Mostly I just have questions and mild suggestions, but a couple things look wrong.