Fix: adding isCanonical lately after removing falsy items

[dinhtungdu]

Description of the Change

In #71, we changed the tracking data sent to Sophi collector to send isCanonical value. This change introduces another issue: we're sending empty array and false values as well. We only need a boolean value for isCanonical field, so this PR reverts the change made in #71 and adds the isCanonical key after filtering the tracking data.

Verification Process

Ensure the tracking data doesn't contain empty strings, empty arrays, and false (except isCanonical field).

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

Changelog Entry

[felipeelia]

The change makes sense @dinhtungdu! While reviewing it, I've noticed that the example introduced in #71 probably should be adjusted to the following (see the number of accepted parameters there). It probably can be handled through a different PR though.

add_filter(
	'sophi_post_content_type',
	function( $type, $post ) {
		// You logic here.

		return $new_type;
	},
	10,
	2
);

Thanks!