Add instrumentation for Azure Service Bus

[russcam]

This PR adds instrumentation for Azure Service Bus when an application is using Microsoft.Azure.ServiceBus 3.0.0+ or Azure.Messaging.ServiceBus 7.0.0+ nuget packages.

Two IDiagnosticListener implementations, one for Microsoft.Azure.ServiceBus and another for Azure.Messaging.ServiceBus, create transactions and spans for received and sent messages:

A new transaction is created when

• one or more messages are received from a queue or topic subscription.
• a message is receive deferred from a queue or topic subscription.

A new span is created when there is a current transaction, and when

• one or more messages are sent to a queue or topic.
• one or more messages are scheduled to a queue or a topic.

A terrform template file is used to create a resource group, Azure Service Bus namespace resource in the resource group, and set RBAC rules to allow the Service Principal that issues the creation access to the resources. The Service Principal credentials can are sourced from a .credentials.json file in the root of the repository for CI, and from an account authenticated with az for local development. A default location is set within the template, but all variables can be passed using standard Terraform input variable conventions.

Closes #1157

[russcam]

An outstanding item is to set the distributed tracing data for receive/receive deferred messages. Messages are typically retrieved and sent in batches however, where each message may represent its own distributed trace. elastic/apm#122 proposes introducing a links property to capture each. Both Microsoft.Azure.ServiceBus and Azure.Messaging.ServiceBus expose the linked traces.

[apmmachine]

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Build stats

• Build Cause: Pull request #1225 updated

• Start Time: 2021-03-30T06:23:37.126+0000

• Duration: 58 min 22 sec

• Commit: 5afeb85

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Failed	0
Passed	19155
Skipped	64
Total	19219

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[russcam]

Going to rebase this against master, to pick up #1240 to run tests on CI

[gregkalapos]

I had a first look, very nice 👍

I added some comments below. On the central config part: I'm not sure it's worth the effort to make the new config runtime changeable right now in this PR - if it turns out to be more work, I think it's totally fine to do it in a follow up - just update the doc in that case.

[gregkalapos]

Suggested change

	==== `IgnoreMessageQueues` (added[1.9])
	==== `IgnoreMessageQueues` (added[1.10])

[gregkalapos]

Here we'll need something like this:

 _centralConfig.IgnoreMessageQueues ?? _wrapped.IgnoreMessageQueues;

_centralConfig.IgnoreMessageQueues doesn't exist yet, that's what we should implement and parse in CentralConfigReader, otherwise it'll only return values from the local config.