Statusbar improvements

There are three individual changes:

1

Allow the editor to occupy maximum space.

It takes minimal space by default now. If you open "Find" or "Goto Line", the widget adjusts to take more space. When you close it, it goes back to being minimal.

2

Lazy load ModeMenuList. It is not needed immediately, so no need to load it. Profiling shows it takes a sizeable portion of the time spent at startup

3

If there are no dictionaries available, hide the spellcheck button in statusbar.

Also, avoid create actions with no string in statusbar.

4

Make it so that view bar widgets don't replace the statusbar but appear on top of it.