add directive grouping

oceanwind has introduced the awesome idea of variant grouping (sm:(...) hover:(...)).

In beamwind we've added directive grouping as well.

Directives with the same prefix can be grouped using parenthesis. Beamwind will expand the nested directives; applying the prefix to each directive in the group before translation. For example:

ow`text(center bold gray-500)`)
// => text-center text-bold text-gray-500

ow`divide(y-2 blue-500 opacity(75 md:50))`
// => divide-y-2 divide-blue-500 divide-opacity-75 md:divide-opacity-50

ow`w(1/2 sm:1/3 lg:1/6) p-sm`
// => w-1/2 sm:w-1/3 lg:w-1/6 p-sm

Some directives like ring need to be applied as is. For that case you can use the special & directive which is replaced with the current prefix:

ow`ring(& ping-700 offset(4 ping-200))`)
// => ring ring-ping-700 ring-offset-4 ring-offset-on-ping-200

I think it would be good if both libraries would support the same string syntax. I try to tackle this on the weekend. But as oceanwind has a different parsing approach it may take some time. I'll report my findings ...

Start by locating oceanwind's parsing and translation entry points, since the issue says its parsing approach differs from beamwind. Implement the demonstrated parenthesized directive groups, including nested groups, responsive prefixes, and the special & prefix, then verify the examples expand to the shown directives.