[filters] [pricing-url] Updated the pricing_url filter so that it als…

[fajardoleo]

…o updates the pricing/upgrade submenu item's URL.

[swashata]

@fajardoleo Could you please refactor the pricing_url method and extract the logic to apply the filter in a private function

function pricing_url(...) {
  $url = ...;

  return $this->get_pricing_url_with_filter( $url );
}

private function get_pricing_url_with_filter( $url ) {
  return $this->apply_filters( 'pricing_url', $url );
}

Then here, instead of calling the filter ad-hoc, you can do

$custom_pricing_url = $this->get_pricing_url_with_filter( null );

This will result in a single source of truth where the filter pricing_url is applied so it less error prone. Thanks.

[swashata]

LGTM 👏