Add `%{all}` interpolation variable

[nikitabobko]

The proposal:

$ aerospace list-windows --format '%{all}' --json
[
  {
    "app-bundle-id" : "org.alacritty",
    "app-bundle-path" : "/Applications/Alacritty.app",
    "app-exec-path" : "/Applications/Alacritty.app/Contents/MacOS/alacritty",
    "app-name" : "Alacritty",
    "app-pid" : 15052,
    ...

Motivation: Exploring all possible variables in interactive way

Requirements: %{all} requires --json flag

[BenjaminBini]

Hi,

Was my implementation bad?

Or should I add doc and tests to it?