Update support forum ratings component

[StevenDufresne]

This PR updates the support forum reviews stars & bars to use the shared component.

Related: WordPress/wporg-mu-plugins#633, #380

Important

The forums display more precise rating numbers, while the new components round ratings to the nearest 0.5. Since we already use the new components in multiple places, if we want to keep the current precision, we should do it everywhere at once in the new components.

Considerations

The ratings-stars and ratings-bars components expect the context to contain postId. However, based on how bbPress works and how it's been modified, the postId is not set.

As a result, I've made use of the render_block_context block to set it. we still don't use that in wporg_set_rating_data, as we need to call wporg_support_get_compat_object to get all the relevant data. It feels a bit silly, but feels better than the alternative. The alternative would be to change the blocks to not return if the post_id is not set. That feels less predictable.

I've also done some minor styling updates.

Screenshots

Before	After