feat: move all window to specific workspace

[Muffeter]

#750

This PR implements a new feature allowing users to move all windows to a specified workspace using custom key bindings.

usage:

  - commands: ["move-all --workspace 1"]
    bindings: ["alt+q+1"]

[lars-berger]

using the InvokeMoveCommand here will cause its flags to show as flags for move-all (e.g. move-all --direction <direction> even though that's not implemented)

would suggest creating a separate struct for move-all's arguments

[lars-berger]

should instead loop over the top-level children of the workspace (this will include both windows + split containers) and call move_container_within_tree on them to the target workspace.

pseudo-code:

let current_workspace = ...
let target_workspace = ...
let children = current_workspace.children();

for children {
  // move workspace children to target workspace
  move_container_within_tree( ...)

  // yoinked from L44-52 of `move_workspace_in_direction.rs`
  window.set_has_pending_dpi_adjustment(true);
  
  window.set_floating_placement(
    window
      .floating_placement()
      .translate_to_center(&workspace.to_rect()?),
  );
}