[split] Move gitstatus theme to oh-my-fish/theme-gitstatus

https://github.com/oh-my-fish/theme-gitstatus

themes/gitstatus/README.md

-## GitStatus
-
-![GitStatus](https://github.com/godfat/fish_prompt-gitstatus/raw/master/gitstatus.png)
-
-#### Characteristics
-
-* Displays host information in the command prompt when connected via ssh.
-
-* Displays git information in the command prompt when inside a git repository.
-
-  - Shows current branch name.
-  - Shows * if working copy is dirty.
-  - Shows # if everything is staged.
-  - Shows no indicators if the working copy is clean.

themes/gitstatus/fish_prompt.fish

-# name: GitStatus
-# Find latest version from: https://github.com/godfat/fish_prompt-gitstatus
-
-function _git_branch_name
-  echo (command git symbolic-ref HEAD ^/dev/null | sed -e 's|^refs/heads/||')
-end
-
-function _git_status_symbol
-  set -l git_status (git status --porcelain ^/dev/null)
-  if test -n "$git_status"
-    # Is there anyway to preserve newlines so we can reuse $git_status?
-    if git status --porcelain ^/dev/null | grep '^.[^ ]' >/dev/null
-      echo '*' # dirty
-    else
-      echo '#' # all staged
-    end
-  else
-    echo    '' # clean
-  end
-end
-
-function _remote_hostname
-  if test -n "$SSH_CONNECTION"
-    echo (whoami)@(hostname)
-  end
-end
-
-function fish_prompt
-  set -l cyan (set_color cyan)
-  set -l normal (set_color normal)
-
-  set -l cwd (set_color $fish_color_cwd)(prompt_pwd)
-  set -l git_status (_git_status_symbol)(_git_branch_name)
-
-  if test -n "$git_status"
-    set git_status " $git_status"
-  end
-
-  echo -n (_remote_hostname) $cwd$cyan$git_status$normal'> '
-end