[alan-divd]

Summary

Adds CRC-64/NVME, the 64 bit counterpart to the existing crc32c, in both a
pure Python and a native Rust implementation.

The layout follows crc32c exactly, so dissect.util.hash.crc64c resolves to
the native version when the extension is available and falls back to Python
otherwise, with crc64c_native and crc64c_python available for picking one
explicitly.

Parameters are polynomial 0xAD93D23594C93659, reflected, with all-ones init
and xorout.

Test plan

• tox run -e py3 passes (163 passed, 63 skipped)
• Matches the official CRC-64/NVME check value,
  crc64c(b"123456789") == 0xae8b14860a799888
• Cross-checked against an independent from-spec bitwise reference
  implementation rather than only against itself
• Native and Python agree over 300 randomized inputs, including chunked
  updates composed via the value argument
• The shared crc64c fixture runs every case against both
  implementations, matching how crc32c is tested