Added dry run of VIP Search index version corruption detection

In order to provide stable and robust index versioning for our search offering, we need to be able to detect and heal any issues with the versioning data.

This feature is the first step towards that goal. It detects index versioning issues and logs them without performing any actions so we can identify any potential issues before rolling this out to all VIP Search users.

There will be an additional change in the future to allow this to run for real once we’ve verified everything operates as we intend.

https://github.com/Automattic/vip-go-mu-plugins/pull/1881