Introduce `entity_goto()` shortcut for `backdrop_goto()` on Entity paths

Description of the need

Redirecting to a node or other entity page is unnecessarily cumbersome. Common approaches include:

// Manual assembly for known entity types:
backdrop_goto('node/' . $node->nid);

// Using URI for general entities:
$uri = $entity->uri();
backdrop_goto($uri['path'], $uri['options']);

// Trying to shorthand the above into a single line:
backdrop_goto($entity->uri()['path']);

Proposed solution

Create a short-hand wrapper function around backdrop_goto() that makes redirecting to entities easier.

function entity_goto(Entity $entity) {
  $uri = $entity->uri();
  backdrop_goto($uri['path'], $uri['options']);
}

Alternatives that have been considered

Maybe also create $entity->goto() method?