Use gitoxide crates to simplify code

[Joshix-1]

1. in HooksPaths::run_hook_os_str in git2-hooks/hookspath.rs

          This is also a capability of `gix-command`, but it's also just done if the command can be converted to bytes at least.
   

Originally posted by @Byron in #2483 (comment)

2. in sh_path in git2-hooks/hookspath.rs

          One could consider to use `gix_path::env::shell()` here.
   

Originally posted by @Byron in #2483 (comment)

[Joshix-1]

Using gix_path::env::shell() should be a straight forward and easy change.

gix-command is too complicated for me to judge whether it's an easy replacement

[Byron]

Thanks for keeping track of this.

I think it's fair to close this issue once #2612 is merged as well, there is no need to force gix in. The plan is to eventually offer gix-hooks anyway.

[extrawurst]

Closed as of #2612