Update Instrumentation to support RabbitMQ 7+

[tippmar-nr]

RabbitMQ v7.0.0 targets .NET Standard 2.0 and .NET8 only, and brings significant breaking changes to the public API, including async methods everywhere.

Update instrumentation and integration tests to support the latest version.

Also update Dotty config to re-enable checking for RabbitMQ updates.

Note that this update is currently blocked by our lack of support for ValueTask<T> return type.

[workato-integration]

https://new-relic.atlassian.net/browse/NR-340747