Adding commented protocols to appropriate samples

[danhellem]

Checklist

• [x] I have read the [contribution guidelines] (https://github.com/Azure/azure-iot-sdk-node/blob/master/.github/CONTRIBUTING.md).
• [ ] I added or modified the existing tests to cover the change (we do not allow our test coverage to go down).
• If this is a modification that impacts the behavior of a public API
  • [ ] I edited the corresponding document in the devdoc folder and added or modified requirements.

Reference/Link to the issue solved with this PR (if any)

Description of the problem

Getting customer feedback on how to use other protocols besides mqtt. Noticed that many of our samples do not have the block for customers to choose.

var Protocol = require('azure-iot-device-mqtt').Mqtt;
// const Protocol = require('azure-iot-device-amqp').AmqpWs;
// const Protocol = require('azure-iot-device-http').Http;
// const Protocol = require('azure-iot-device-amqp').Amqp;
// const Protocol = require('azure-iot-device-mqtt').MqttWs;

Description of the solution

Added block to each sample.

[danhellem]

/azp run Azure.azure-iot-sdk-node

[azure-pipelines[bot]]

No pipelines are associated with this pull request.

[danhellem]

/azp run Azure.node-canary (Windows Node 12.x)

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[danhellem]

/azp run

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Azure Pipelines successfully started running 2 pipeline(s).

[danhellem]

/azp run

[azure-pipelines[bot]]

Azure Pipelines successfully started running 2 pipeline(s).