MDNS optimizations and refactorings (#921)
* Exclude TCP and ICD TXT data because not used
According top specs these two are optional and at least ICD should not be there if ICD is not supported, so comment them out until we add support
* Add T/ICD TXT defaults when not provided
including handling T=1 special case
* Add validation for some CommissioningInfos
according to specs
* Migrate to JS privates
* Changelog
* Adjust MDNS tests
