Resolve "Spike: Test cypress as replacement for taiko"

Closes #1054 (closed)

Todo

• Properly close f#$king welcome wizard modal (see https://open.greenhost.net/stackspin/nextcloud/-/jobs/237484)
• Successfully test basic NC + OO
• Fix random errors like this

AssertionError: Timed out retrying after 4000ms: Expected to find element: `[name="frameEditor"]`, but never found it.
  at Context.frameLoaded (https://files.varac-test.stackspin.net/__cypress/tests?p=cypress/e2e/test-nextcloud.cy.js:241:15)

• Port all steps from taiko test (#1058)