Langmap feature support

[Opisek]

I am an avid user of Vim's "langmap" feature for remapping the whole keyboard in normal and visual mode. That's unfortunately not supported by CodeMirror or Obsidian, so I had to hack together a little plugin using switching the system's keyboard layout when necessary: obsidian-vim-langmap

Now, I've noticed that this plugin also tackles a similar matter in form of "constant layout for normal mode" setting. Furthermore, I was able to see your usage of overriding the default `onKeydown' event. I like that approach much better than what I wrote, but I was never able to get this feature of your plugin to work on my setup (hence I wrote my own solution in first place).

That brings me to the point I want to make: I would gladly implement the whole langmap feature of Vim into your plugin. You can take my previous work in that department as reference of what I would like to achieve: VSCodeVim Langmap Before I do so, I would like to ask if that's something you'd be interested in merging once finished.

[yeongbin-jo]

:+1: