Special purpose CNs database agreed with CN's payloads

[vncoelho]

I propose something like Blobs,

Special blob-carrying txs can be sent in order to save special information (maybe, in the first phase, from whitelisted contracts only).
The hash of the accumulated state is only passed through CN's payloads.

This is a temporary state and can serve for different purposes, such as storing parameters like #4337 (review)

• TXs (i.e blob-carrying txs) do not need to be saved at all
• Users (projects) can send then if whitelisted
• Information can be available within a given time limit
• Some assistive network parameters can live there and maybe just allowed to be modified from CN's payloads (such as MillisecondsPerBlock, MaxValidUntilBlockIncrement, MaxTraceableBlocks, ...)
• Other information that may become necessary may live there

If the idea goes in front we can create a formal proposal