vim-surround support #92

I think the one thing that vim mode in bootdev just really lacks is not having support for vim-surround. Vim mode would be substantially easier to use with just this one addition. There's a million things vim users could ask for, but I think we could all agree on vim-surround being one of the most needed additions. There is no details on bootdev's implementation of vim that I could find, so I don't really have any suggestions other than the plethora of implementations in popular text editors like vscode, obsidian (with codemirror editor).