Query: Add more context to the split_the_query filter.

 Add more context to the `split_the_query` filter by adding two new parameters: '$old_request' and '$clauses'. This enriches the filter with additional information about the SQL query before the query is run, enabling developers to have more context to help decide if a query should be split. 

Props spacedmonkey, shailu25, rcorrales, tillkruess.
Fixes #59514.

git-svn-id: https://develop.svn.wordpress.org/trunk@58180 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/class-wp-query.php

@@ -3313,11 +3313,24 @@ public function get_posts() {
 			 * complete row at once. One massive result vs. many small results.
 			 *
 			 * @since 3.4.0
+			 * @since 6.6.0 Added the `$old_request` and `$clauses` parameters.
 			 *
 			 * @param bool     $split_the_query Whether or not to split the query.
 			 * @param WP_Query $query           The WP_Query instance.
+			 * @param string   $old_request     The complete SQL query before filtering.
+			 * @param string[] $clauses {
+			 *     Associative array of the clauses for the query.
+			 *
+			 *     @type string $where    The WHERE clause of the query.
+			 *     @type string $groupby  The GROUP BY clause of the query.
+			 *     @type string $join     The JOIN clause of the query.
+			 *     @type string $orderby  The ORDER BY clause of the query.
+			 *     @type string $distinct The DISTINCT clause of the query.
+			 *     @type string $fields   The SELECT clause of the query.
+			 *     @type string $limits   The LIMIT clause of the query.
+			 * }
 			 */
-			$split_the_query = apply_filters( 'split_the_query', $split_the_query, $this );
+			$split_the_query = apply_filters( 'split_the_query', $split_the_query, $this, $old_request, compact( $pieces ) );
 
 			if ( $split_the_query ) {
 				// First get the IDs and then fill in the objects.