[ecovacs] Login flow does not work (anymore)

Ecovacs recently made some server side changes that break the login flow, particularly they require now each new `deviceId` to be verified via an emailed code. See https://github.com/home-assistant/core/issues/176484 for an analysis of the behavior change. For us, this means - reviewing whether a [per-thing device ID](https://github.com/openhab/openhab-addons/blob/main/bundles/org.openhab.binding.ecovacs/src/main/java/org/openhab/binding/ecovacs/internal/handler/EcovacsApiHandler.java#L122) really is required - adjusting to the API changes - provide some way to enter the emailed code @lsiepel Any ideas for the latter point? I'm currently not sure what the best way to implement something like that would be. ## Current Behavior - Create Ecovacs API thing - Provide user name and password - Thing does not come online ## Expected behavior - Thing asks for verification code and comes online afterwards