Migrating CallToken code to service_queue module so it can be shared

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Problem/Motivation

The CallbackToken private methods need to move to the service_queue module so it can be re-used by other modules, notably the RabbitMQ module I am working on as an extra provider for triage_mail. See #3638213: Add a CallbackToken service so we can move it out of the service_bus_provider module as well, because these two issues go together, although the service_queue issue should be merged first.

This MR also adds a preuninstall hook that just ensures the service_bus_provider module cannot be removed accidentally if there are configured queues for it. Enforces removing the queues before you remove the module.

Remaining tasks

None

User interface changes

None

API changes

None

Data model changes

None