Add a jetbrains-like Toggle All Docks action (#40567)

The current Jetbrains keymap has `ctrl-shift-f12` set to
`CloseAllDocks`. On Jetbrains IDEs this hotkey actually toggles the
docks, which is very convenient: You press it once to hide all docks and
just focus on the code, and then you can press it again to toggle your
docks right back to how they were. Unlike `CloseAllDocks`, a toggle
means the editor needs to remember the previous docks state so this
necessitated some code changes.

Release Notes:

- Added a `Toggle All Docks` editor action and updated the keymaps to
use it

assets/keymaps/default-linux.json

@@ -609,7 +609,7 @@
       "ctrl-alt-b": "workspace::ToggleRightDock",
       "ctrl-b": "workspace::ToggleLeftDock",
       "ctrl-j": "workspace::ToggleBottomDock",
-      "ctrl-alt-y": "workspace::CloseAllDocks",
+      "ctrl-alt-y": "workspace::ToggleAllDocks",
       "ctrl-alt-0": "workspace::ResetActiveDockSize",
       // For 0px parameter, uses UI font size value.
       "ctrl-alt--": ["workspace::DecreaseActiveDockSize", { "px": 0 }],