Core AMQP cleanup for v2

[ramya-rao-a]

This PR addresses the points in #12116 (comment) to clean the public API surface of @azure/core-amqp package.

Context: @azure/amqp-common is the package with common code for Event Hubs v2 and Service Bus v1 packages. When we started working on Event Hubs v5 based on the new guidelines, we copied this package, named it @azure/core-amqp, added TokenCredential support and made it easier to have retries. What we missed was doing a cleanup of things that we don't really need exported from here.

This PR does the said cleanup as follows:

• Stop exporting things that are not currently used by either Service Bus or Event Hubs packages
  • AsyncLockOptions
  • executePromisesSequentially
  • Func
  • getNewAsyncLock
  • isNode
  • randomNumberFromInterval
  • Timeout
• Remove all IotHub related artifacts. These existed to support the IotHub support we had in Event Hubs v2 which has since been removed in Event Hubs v5 for a better separation of concerns
  • IotHubConnectionConfig
  • IotHubConnectionStringModel
  • IotSharedKeyCredential
  • isIotHubConnectionString
• With Implement a Service Bus Shared Access Key Credential #11891 and Implement an Event Hubs Shared Access Key Credential #11892, both Service Bus and Event Hubs packages will have dedicated SharedKeyCredential classes with the class name reflecting the service so that one doesnt see a generic exported class and attempt to use it with other services. As part of this I am
  • removing the SharedKeyCredential class & its tests from @azure/core-amqp and copying them to Service Bus and Event Hubs packages
  • remove credential from the ConnectionContextBase in @azure/core-amqp and have the ConnectionContext in SB & EH packages house it
  • update negotiateClaim() to take token string instead of the AccessToken. With this, @azure/core-amqp need not re-export things from @azure/core-auth
• Avoid having anything that is specific to Event Hubs or Service Bus as a service in @azure/core-amqp
  • With Implement a Service Bus Connection String Parser #11893 and Implement an Event Hubs Connection String Parser #11894, SB & EH will have their own parsers and interfaces to represent the parser output. So, all the "*ConnectionStringModel" interfaces are not needed anymore
  • EventHubConnectionConfig is moved to EH package along with its tests
• Avoid re-exporting things from rhea-promise. EH & SB already have a dependency on this and can use things from it directly

EH live tests and SB live tests have been run

[HarshaNalluru]

NIT

Suggested change

	- removing exports that are either not used by either `@azure/event-hubs` and `@azure/service-bus` packages (which are the two main consumers of this package)
	- removing exports that are neither used by `@azure/event-hubs` nor `@azure/service-bus` package (which are the two main consumers of this package)

[richardpark-msft]

Looks great, core-amqp feels much healthier.