Introduce new object type to store additional configuration/data/entities in adapters

[Apollon77]

Why
Adapters often have additional configuration data (e.g. tokens or other type of "entities") where it is not ideal to store them in the instance object (because changeing them restarts the instance). For now we have no real place to store these data (especially if they or not a "device", "channel" or "state" (folder feels not natural for such data).
We see questions from deveopers here and there on how/where to best store such data. The alternatives are often "store ina file in iobroker-data" (which then has issues when the adapter is moved to an other host!)

What is the idea?
The idea is to define a new object type (or maybe reuse "config"?) which can be stored in an adapter instance in various places. The common area only have a name and always "expert:true" to hide for normal users.

We also enhance admin adapter to include these objects into the json which is returned for "download instance config" and also accept this including recreation of the objects when uploading such a configuration.

Why not use "meta"?
Because meta objects are defining also "filesystem storage places" which is not required here.

[Apollon77]

Maybe we simply reusew "config"? Then it would be just a typem update and "dcumetatioN" (and the amin adjustment)