Upgrade RabbitMQ.Client to v7

[lechu445]

What would you like to be added:
To upgrade HealthChecks.RabbitMQ from v6 to v7.

Why is this needed:
Because v7 has lots of API changes in compare to v6, HealthChecks.RabbitMQ blocks users from upgrade the RabbitMQ client in their apps.

More info

• Release notes: https://github.com/rabbitmq/rabbitmq-dotnet-client/releases/tag/v7.0.0
• Migration guide: https://github.com/rabbitmq/rabbitmq-dotnet-client/blob/main/v7-MIGRATION.md
• Discussion topic about migration: Migration Guide? rabbitmq/rabbitmq-dotnet-client#1720

[czinegeroland]

It is mandatory to work with MassTransit 8.3.2. It is already using RabbitMQ.Client v7. https://masstransit.io/support/upgrade#version-832

[eerhardt]

Add support for RabbitMQ.Client version 7. (Xabaril/AspNetCore.Diagnostics.HealthChecks#2323) adds support for version 7.

The strategy we are taking is to support both version 6 (with the existing package) and add a new package to support version 7. At
a later date (probably on the next major release) we can swap the dependencies. See the PR for more detail on the plan.