meta: introduce Cypress end-to-end testing (via #4827)

* `test/e2e` -> `test/e2e-selenium`

* add Cypress

* ESLint fixes

* MOAR cypress

* `integration` -> `tests`

* wire Cypress up to a hot e2e server

* linter fixes

* don't run in CI

test/e2e-selenium/specs/bugs/4536.yaml

@@ -0,0 +1,9 @@
+swagger: '2.0'
+info:
+  version: 0.0.0
+  title: test
+paths: {}
+
+definitions:
+  ModelName:
+    title: TitleName