add support for valid values for (de)Humidifier target state

[gjvanderheiden]

Pull Request Checklist

Please confirm that you've done the following when opening a new pull request:

• For fixes and other improvements, please reference the GitHub issue that your change addresses.
• For fixes, optimizations and new features, please add an entry to the CHANGES.md file.
• Run mvn compile before committing, so that the auto-code formatter will format your changes consistently with the rest of the project.

[gjvanderheiden]

linked issue should be 119

[yfre]

looks good for me