Explore allowing cy command usage in cy.intercept callbacks

[flotwig]

Current behavior:

cy commands are not explicitly treated differently when called from inside cy.route2 callbacks.

Desired behavior:

Cypress generally stops users from writing non-deterministic tests, and using cy commands inside of request/response callbacks would cause non-determinism.

cy commands should fail when called from inside cy.route2 callbacks with a clear error message explaining why.

Perhaps cy.now should remain, so users can have a backdoor to access Cypress commands directly