Add command "Focus Active Editor"

[hisbvdis]

After focused panel changing it is useful to come back to the editor, that was last active.
VSCode command: workbench.action.focusActiveEditorGroup
For example, when the editor is focused, I want to set keybinding to change terminal panel height.
So, I need to specify the following keybindings:

1. Change focus to the "Terminal"
2. Change height
   3. Come back to the active editor

I had this keybinding in the VSCode:

{
  "key": "ctrl+alt+=",
  "command": "runCommands",
  "args": {
    "commands": [
      "workbench.action.focusSideBar",
      "workbench.action.increaseViewSize",
      "workbench.action.increaseViewSize",
      "workbench.action.focusActiveEditorGroup"
    ]
  },
  "when": "editorFocus || !panelFocus"
},

And I try to do the same in Zed

{
  "context": "!Terminal",
  "bindings": {
    "ctrl-`": "terminal_panel::ToggleFocus"
  }
},
{
  "context": "Terminal",
  "bindings": {
    "ctrl--": [
      "workspace::DecreaseActiveDockSize",
      {
        "px": 200
      }
    ]
  }
},
{
  "context": "!Terminal",
  "bindings": {
    "ctrl--": ["workspace::SendKeystrokes", "ctrl-` ctrl-- ctrl-e"]
  }
},

I feel lack of the command, that allows to come back to the last active editor

[SomeoneToIgnore]

To note, active === focused in Zed's terms hence this is quite a tautology to process.

#34495