Update message type in prefetch-on-demand controller

[Spomky]

The message type in the workbox.messageSW function call was updated from "PREFETCH" to "CACHE_URLS". Additionally, the payload property name was changed from "urls" to "urlsToCache" to reflect the latest method call changes.

Target branch: 1.1.x Resolves issue #

• [x] It is a Bug fix
• [ ] It is a New feature
• [ ] Breaks BC
• [ ] Includes Deprecations