Migrate Nord repositories from `arcticicestudio` to `nordtheme`

[svengreb]

The latest “Northern Post — The state and roadmap of Nord“ announcement described the plans for the migration to Nord‘s new home home on GitHub and this epic (GitHub tasklist) is used to track to overall process. For a better visualization, with a time-based structure and general overview see the “Roadmap ⧚“ view of Nord‘s “Planning & Roadmaps“ project board as well as the “Active ↻“ view for the current iteration.

The main goal is to migrate the repositories itself to this new nordtheme organization, including…

• …adjustments of any hyperlinks to previous arcticicestudio references as well as other, already migrated, repositories.
• …adjustments of any copyright information, removing Arctic Ice Studio as Nord brand due to its retirement.
• …adaption to updated documentation and style conventions which reduces the need to solve this through individual issues again afterwards.
• …adaption to Nord‘s new “Planning & Roadmaps“ project board by adding existing, already triaged or active, issues and preparing “fresh“ issues for the follow-up triaging later on.

  
  ### Tasks

• [ ] https://github.com/nordtheme/vim/issues/335
• [ ] https://github.com/nordtheme/visual-studio-code/issues/258
• [ ] https://github.com/nordtheme/iterm2/issues/13
• [ ] https://github.com/nordtheme/tmux/issues/79
• [ ] https://github.com/nordtheme/dircolors/issues/32
• [ ] https://github.com/nordtheme/emacs/issues/122
• [ ] https://github.com/nordtheme/gnome-terminal/issues/38
• [ ] https://github.com/nordtheme/alacritty/issues/33
• [ ] https://github.com/nordtheme/jetbrains/issues/208
• [ ] https://github.com/nordtheme/xresources/issues/15
• [ ] https://github.com/nordtheme/terminal-app/issues/13
• [ ] https://github.com/nordtheme/xfce-terminal/issues/14
• [ ] https://github.com/nordtheme/sublime-text/issues/37
• [ ] https://github.com/nordtheme/slack/issues/20
• [ ] https://github.com/nordtheme/hyper/issues/38
• [ ] https://github.com/nordtheme/notepadplusplus/issues/21
• [ ] https://github.com/nordtheme/tilix/issues/19
• [ ] https://github.com/nordtheme/terminator/issues/18
• [ ] https://github.com/nordtheme/termite/issues/13
• [ ] https://github.com/nordtheme/atom-ui/issues/91
• [ ] https://github.com/nordtheme/konsole/issues/14
• [ ] https://github.com/nordtheme/web/issues/241
• [ ] https://github.com/nordtheme/xcode/issues/15
• [ ] https://github.com/nordtheme/atom-syntax/issues/71
• [ ] https://github.com/nordtheme/putty/issues/7
• [ ] https://github.com/nordtheme/gedit/issues/20
• [ ] https://github.com/nordtheme/highlightjs/issues/22
• [ ] https://github.com/nordtheme/mintty/issues/7
• [ ] https://github.com/nordtheme/conemu/issues/6
• [ ] https://github.com/nordtheme/guake/issues/8
• [ ] https://github.com/nordtheme/eclipse-syntax/issues/15
• [ ] https://github.com/nordtheme/brackets/issues/9
• [ ] https://github.com/nordtheme/coda/issues/8