space-within-parens should allow exceptions

[mmakrzem]

I should be allowed to specify that I want a space inside parentheses but no space if there is nothing being passed in. ie:

Foo( 2 ); //good
Bar(); //also good

as it is now, I have to place a space inside the second case. ie Bar( ); //boo I don't want to have to insert a space between the empty parentheses

See how eslint handles spaces inside parentheses here: https://eslint.org/docs/rules/space-in-parens

[ajafff]

I'd like to limit the scope to always allow '()' if there is nothing between the parens.
Exceptions like in ESLint can be implemented later on.

[ajafff]

Fixed by #3513