After moving email-related routes from `general/...` to `email/...`, the detail and "new" sub-pages still pointed back to `SettingsPath.Workspace` (the General page) on the second breadcrumb crumb and after delete/cancel. Point them at `SettingsPath.WorkspaceEmail` and rename the crumb label from "General" / "Emailing Domains" to "Email". Caught by sentry and cubic on #21008.