Add `cypress-skip-test` library (#15200)

* Add `cypress-skip-test` library

This is the official Cypress library for conditionally skipping/running tests.
https://github.com/cypress-io/cypress-skip-test

* Enable `cy.onlyOn` and `cy.skipOn` custom commands in all tests

Reference: https://github.com/cypress-io/cypress-skip-test#example