Create a Selenium-based testing framework

[mbaas2]

• first test "Buttons" (which is thought of as a "testable demo"), then look at a "not so easily testable" one and adopt demo as neccessary

[sloorush]

These tests exist in branch 30-testing. We are currently experimenting with playwright. As part of that we will ensure parity with the existing tests.

Playwright tests for demos exist here: https://github.com/cursork/ewcdemotest