Call BotFrameworkAdapter.useWebSockets() when the upgrade request hits the messaging endpoint

[stevengum]

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Sample information

1. Sample type: samples\
2. Sample language: [Node.js and TypeScript]
3. Sample name: Samples that use WebSockets for Direct Line Speech

Describe the bug

Add the logic to samples so that it only processes any Upgrade requests against its messaging endpoint.

Expected behavior

Any Upgrade requests should not be automatically processed unless against the messaging endpoint.

Either we change the samples to track the correct messaging endpoint, or we add comments to indicate to developers that their bots should only attempt the Upgrade request when it receives the request against its messaging endpoint.

[bug]

[stevengum]

Derived from https://github.com/microsoft/botbuilder-js/issues/1387.