Delete Customers and Sites Functionality

We need to replicate existing Job and WO functionality in order to help with deleting customers and sites.

Follow the existing Job and WO functionality to:

- Mark the local database records as deleted
- Mark the sfsp add_db_object_update_status() tracking record as deleted
- Attempt to delete in SF

I don't think SF will let us if there are related records but we can try and if not then return an error message that the user has to "move the records associated with this Customer/Site within Salesforce before deletion" - still make sure the other db records are marked as deleted in this case

- Additionally add same delete attempt in Salesforce for Jobs and WOs with the same response handling
- We cannot delete in Spectrum, so there should be the same warning/info as shown for Jobs and WOs

Locate the existing Job and WO deletion entry points, including their local database updates, sfsp add_db_object_update_status() tracking, Salesforce attempts, and Spectrum messaging. Trace those flows before implementing equivalent Customer and Site handling, plus the requested Job and WO response behavior; done means records are marked deleted, Salesforce failures return the specified guidance, and Spectrum shows the same warning or information.

Written by the indexing model from the issue text.