* ref #3958, support utf16 fragments on the deeplink plugin
* put -> head for UTF16 operation
this is a temporary fix, eventually we will run out
of methods and need to use a new targeting strategy
* drop obsolete %20 decoder
* add full test suite for UTF16 operation
* use encodeURIComponent when setting hash
* drop obsolete test cases
* add tests for operation lacking an operationId
* add deep linking tests for tags/operationIds with underscores
* migrate from `_` to `%20` for deeplink hash whitespace escaping
* add backwards compatibility for `_` whitespace escaping
* update util unit tests
* `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
