Enable folding of code blocks

[YaPravaATyNet]

No description provided.

[kornilova203]

Overall looks good
Couple of things that need to be fixed:

1. events block is not folded

   classdef A
     events (NotifyAccess = protected)
        ToggledState
     end
   end

2. Maybe list of super classes should not be folded (at least in Kotlin they are visible)
3. For some reason if I have an unfinished statement at the end then folding disappears

   if 1
   end
   if

4. Function may not contain end but it still should be folded

    function hello
    a = 1

[kornilova203]

Also looks like it's easy to add a folding test see JsonFoldingTest