Fix: open on linux / xdg-open output's parent dir

[tom-gora]

Description

Just a simple condition branch added to commands/open because this was erroring out on linux.
No way was set for automatic open if is_unix was true. PResumably b/c it is tricky to determine what is the default file manager in variety of linux environments. The best approximation I came up is directing xdg-open to parent dir of the output file. It should open the location in preferred file manager without focusing on the file, but it should be
enough to improve the flow, rather than simply erroring out.

Type of change

• Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

none
Configuration:

• Neovim version (nvim --version):
  NVIM v0.10.4
  Build type: RelWithDebInfo
  LuaJIT 2.1.1720049189
  Run "nvim -V1 -v" for more info

• Operating system and version:
  Fedora Linux 40 Wayland Environment

Checklist

• [ x] My code follows the style guidelines of this project (stylua)
• [x ] I have performed a self-review of my own code
  - [ ] I have commented my code, particularly in hard-to-understand areas NOT APPLICABLE/TOO SIMPLISTIC
  - [ ] I have made corresponding changes to the documentation NOT APPLICABLE
• [ x] I did read the CODE OF CONDUCT
  and I agree to follow it.

[tom-gora]

BTW. Sorry if I did something wrong. My first PR ;)

[AlejandroSuero]

@tom-gora Thank you for noticing, I overlooked it.

[AlejandroSuero]

BTW. Sorry if I did something wrong. My first PR ;)

The only thing that was "wrong" was not using the conventional-commits style of commit message, but it's fine.

[tom-gora]

BTW. Sorry if I did something wrong. My first PR ;)

The only thing that was "wrong" was not using the conventional-commits style of commit message, but it's fine.

Thanks for the feedback :)