Potentially Remove Python-based Assembler/Disassembler

[hawkinsw]

It appears to be less than useful. I was unable to get it to execute with a modern version of Python. Given that bpf_conformance has an awesome assembler, it seems like we could let this go. If you give me the word, I'd be happy to make the PR.

[Alan-Jowett]

Thanks for raising this, @hawkinsw — go for it! 🚀

I took a look at what the Python assembler/disassembler provides vs what bpf_conformance already has, and the conformance tools are a strict superset:

• Full RFC 9669 v1–v4 coverage (170+ mnemonics) vs the Python tools which are missing atomics and some newer opcodes
• Same AT&T-style syntax (%r0, [%r1+off], labels, etc.) so existing tests/*.data asm sections should be compatible
• Already in the repo as a submodule

Here's what I think the cleanup would involve:

1. Port or remove the 3 Python test files — test_framework/test_assembler.py, test_disassembler.py, test_roundtrip.py (they could be rewritten to exercise bpf_asm/bpf_disasm instead, or dropped if the conformance project already has equivalent coverage)
2. Update libfuzzer/split.sh — it currently calls bin/ubpf-disassembler; switch to bpf_disasm
3. Remove ubpf/, bin/ubpf-assembler, bin/ubpf-disassembler, and requirements.txt
4. Update README.md to reflect the change

Happy to review whenever you have something ready. Thanks!