Remove `orientation_packer` and `no_orientation_mod` feature flags.

[lgarron]

I'm leaning towards making orientation_packer the default (and only) implementation.

[lgarron]

I'm leaning towards making orientation_packer the default (and only) implementation.

I think this is the right choice. It doesn't seem to matter much on Apple Silicon (M1 Max or M2), but really does for whatever the GH Actions runner is using:

https://mastodon.social/@lgarron/110948798868171080

Note that speeds vary by about 1M moves/s, but:

• M1 Max
  • orientation_packer: 34.18M moves/s
  • neither flag: 34.18M moves/s
  • no_orientation_mod: 33.99M moves/s
• GH Actions runner
  • orientation_packer: 20.58M moves/s
  • neither flag: 9.16M moves/s
  • no_orientation_mod: 11.44M moves/s