Hotfix for falsy assertion in focus.swift

#341

The workaround replicates the workaround that was previously written in
WorkspaceCommand:

    // todo drop anyLeafWindowRecursive. It must not be necessary
    if let window = workspace.mostRecentWindow ?? workspace.anyLeafWindowRecursive { // switch to not empty workspace
        state.subject = .window(window)
    } else { // switch to empty workspace
        check(workspace.isEffectivelyEmpty)
            state.subject = .emptyWorkspace(workspaceName)
    }

Sources/AppBundle/focus.swift

@@ -87,10 +87,11 @@ extension Window {
 }
 extension Workspace {
  func focusWorkspace() -> Bool {
- if let w = mostRecentWindowRecursive {
+ // todo unfortunately mostRecentWindowRecursive may recursively reach empty rootTilingContainer
+ // while floating or macos fullscreen windows might be presented
+ if let w = mostRecentWindowRecursive ?? anyLeafWindowRecursive {
  return w.focusWindow()
  } else {
- check(anyLeafWindowRecursive == nil)
  return setFocus(to: LiveFocus(windowOrNil: nil, workspace: self))
  }
  }