[Bug] Add left delim comment before leading space

[Masquue]

Add a new option NERDCommentBeforeLeadingWhitespace or something to allow behavior of AddLeftDelim to be changed to

function! s:AddLeftDelim(delim, theLine) abort
  return substitute(a:theLine, '^\(\s*\)', a:delim . '\1' , '')
endfunction

This behavior can be achieved by setting existing option g:NERDDefaultAlign to 'start' (which is 'none' by default), and this option is used in all formatting commands except \cl (AlignLeft) and \cb (AlighBoth).

Is it a bug or design that using \cl or \cb does not respect the setting of g:NERDDefaultAlign when it is 'start'?