[UPDATE][VIM] Color column 99 in Rust files

As mandated by the official coding style for Rust.

vim/.vim/after/ftplugin/rust.vim

@@ -20,3 +20,7 @@ let b:undo_ftplugin.='|unlet! b:ale_fixers'
 " Automatically format files when saving them
 let b:ale_fix_on_save=1
 let b:undo_ftplugin='|unlet! b:ale_lint_on_save'
+
+" Change max length of a line to 99 for this buffer to match official guidelines
+setlocal colorcolumn=99
+let b:undo_ftplugin.='|setlocal colorcolumn<'