Add sniff for calling WP_Query->get_posts()

Is your feature request related to a problem?

Calling get_posts() directly from WP_Query may be mistaken as a getter for the posts property, however, it is not. Calling this outside of the constructor will add an additional query.

$args = [
  'posts_per_page'      => '10',
  'post_type'           => 'post',
  'post_status'         => 'publish',
  'no_found_rows'       => true,
  'ignore_sticky_posts' => true,
  'cat'                 => 123
];
$my_query = new WP_Query( $args );
$my_posts = $my_query->get_posts();

Describe the solution you'd like

Call the posts property rather than the method.

$my_posts = $my_query->posts;

Start by locating the existing sniff implementations and tests for WordPress or WP_Query method calls. Use the issue's examples to define the target behavior: flag direct WP_Query->get_posts() calls and recommend the posts property, while confirming the behavior is covered by tests.