Browser-based test

[divergentdave]

We should make another private package for a browser-based integration test. It should import the client library, spin up mock HTTP servers for the aggregators, and test the client from within a browser using Selenium or similar.

[jbr]

Some questions/thoughts:

• Mock aggregator or actual janus? Is the intent an end-to-end exercise of the system or an integration test for the cli working in-browser?
• There are two ways people might use the @divviup/dap package -- directly from a cdn in a script tag, or requiring it into an in-browser compiled app like a react app. We probably should test both of these to ensure that the packaging works either way.
• Do we want to try for multi browser testing with playwright or just use puppeteer for chrome and do manual testing for the other browsers?

[divergentdave]

I think a mock aggregator would be fine for this, we've got a separate integration test to cover interop with Janus, and using a mock would help keep the test infrastructure complexity down. I'm mainly interested in confirming that our compilation steps and packaging are working. For that reason, one browser should be fine.