FeatureRequest: Separate sorting into its own component

**Issue Type:**
enhancement

**Description:**
Currently, to the best of my knowledge, the sorting features are embedded in the result components. Perhaps it should be moved into a separate components for added flexibility/customizability?

Interestingly enough, on the ReactiveSearch homepage there is a picture showing a "sort by" dropdown beside the search form. Is this ability supported out of the box or is it a custom component?