botframework-streaming should separate main/browser exports

[compulim]

Versions

master as of right now.

Describe the bug

I briefed @stevengum and @ckkashyap offline on this one.

In https://github.com/microsoft/botbuilder-js/blob/master/libraries/botframework-streaming/src/index.ts, it is exporting namedPipe.js, which depends on Node.js net package.

Instead, we should have 2 entrypoints, one for Node.js and one for browser. For the browser one, it should not export namedPipe.js.

To Reproduce

Steps to reproduce the behavior:

1. Create a Webpack project
2. Include botframework-streaming
3. Run Webpack to bundle

Expected behavior

Webpack should not throw error.

Instead, Webpack is complaining it cannot bundle net package. This is because botframework-streaming/namedPipe.js depends on botframework-streaming.

Additional context

Also same for Node.js, which should not include dependencies that is targeting only browsers.

[bug]

[stevengum]

webpack/webpack#4674

After syncing with @compulim in person, we're going use the package.json's "main" and "browser" field. We'll use either es5-index.js or browser-index.js for the "browser"/ES5-transpiled code.