migrate `examples` to `openApi` part 11: enums; affects [codefactor conda depfu homebrew jsdelivr reddit sourceforge testspace vaadin github] (#9437)

* WIP enums

* WIP moar enums

* add a helper function for extracting enum from route pattern

* add enum schemas to services

* review and improve service names

* convert some more services with enums

* review and improve service names

* fix issue/pull request detail