Add support for error handling for missing comment end

[ydah]

Example:

%{
// Prologue
%}
%%
foo: "baz"
   ;
%%
/* This is a comment

Bison:

tmp/missing.y:8.1-9.0: error: missing ‘*/’ at end of file
    8 | /* This is a comment
      | ^~~~~~~~~~~~~~~~~~~~

Lrama:

# No error

[yui-knk]

I understand the intention however I'm wondering where is the best place to put the logic...