RocketCDN Free Tier: Handle CDN CNAME & ZONE Change for RocketCDN

[jeawhanlee]

Description

When a RocketCDN subscription is active, we need to handle the CNAME change without overriding the CNAME option value if it already has one.
For example, a user who updates to 3.22 with a cname from a different CDN provider should not lose their details after they subscribe to RocketCDN free/paid.

Describe the solution you'd like

• I propose using pre_get_rocket_option{$option_name} to change the cdn_cnames & cdn_zone
• Set the priority to < 10 so that one.com compatibility can take highest priority
• The callbacks will basically check for any form of RocketCDN Subscription and build the cdn_cnames & cdn_zone from the transient stored by the user_client.
• These logic can be added here
• Then I believe we need to update these 2 methods enable & disable to avoid modifying the cdn options and preserve modification only through the UI for BYOCDN

Acceptance Criteria

• GIVEN that RocketCDN subscription is active(either free or paid)
• AND CDN DB options(cdn_cnames & cdn_zone) are empty
  • THEN cdn_cnames & cdn_zone should change on a filter level and CDN DB options should remain empty.

• GIVEN that RocketCDN subscription is active(either free or paid)
• AND CDN DB options(cdn_cnames & cdn_zone) are not empty
  • THEN cdn_cnames & cdn_zone should change on a filter level and CDN DB options values should remain as it is.

Dependency Module

N/A