Update RISCV ISA by parsing binutils

[patrick-rivos]

The RISCV ISA is roughly 5 years outdated at this point. Existing instructions still work great, but there have been new extensions released in the meantime. One of those extensions is the Vector extension, which encodes a fair amount of complexity with its variable length instruction encoding. Vector spec

This PR adds a parser for the RISCV instruction set and references binutils 2.40 as a source of truth. This PR is a draft and still has work to be done (memory reads/writes using vector, actually encoding the binary format, etc.)