Add support to 'NOT LIKE' operator for meta_query

[Rahmon]

Description of the Change

This change adds support to NOT LIKE operator for meta_query.

Alternate Designs

Benefits

Adds a new way to filter posts.

Possible Drawbacks

Verification Process

This has been tested manually adding a custom field using ACF and querying with the operator NOT LIKE.

1. Adds a check box field with the options red, green, and blue;
2. Set this field in some posts;
3. Query using NOT LIKE

$args = array(
	'ep_integrate' => true,
	'meta_query'   => array(
		array(
			'key'     => 'checks',
			'value'   => 'red',
			'compare' => 'NOT LIKE',
		),
	),
);

$the_query = new WP_Query( $args );

Checklist:

• I have read the CONTRIBUTING document.
• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my change.
• All new and existing tests passed.

Applicable Issues

Closes: #2015

Changelog Entry

Added support to NOT LIKE operator for meta_query