Skipping built-in LFS hooks

[zachahn]

Hello!

As I mentioned in #818, I'm working on a very large codebase (3+ gb) that doesn't seem to use LFS. I noticed that git operations were extremely slow, even though git is supposed to work pretty well on large repositories! I believe I found the cause to be Lefthook's LFS hook.

I'd love to be able to skip the LFS hook (only) while running our configured hooks. I have a few ideas (I'm not sure if they're all possible)

1. Continue to run the LFS hook by default, and create a new option like lfs: false or skip_lfs: true
2. Skip the LFS hook by default, and create a new option to opt in with lfs: true
3. Look for a constant time way to determine if LFS hooks should be run automatically

I'd prefer option 3 the most, but if that's not possible, I'd prefer option 2. I've never used LFS, neither at work nor at home, so I'd assume more projects do not use LFS than use it—but that's a total guess of mine. I think I have a constant time way to determine if LFS hooks should run, to check git config get filter.lfs.process, filter.lfs.smudge, and filter.lfs.clean (they're all blank for me). LMK if there's a better way!

I'm happy to work on this! This will honestly save us so much time.

[zachahn]

Closing! See: #879