Enhance stateChangesById for sponsored transactions

[deemru]

Аbstract
Currently there is no trivial way to get how much WAVES sponsor pays for his sponsored asset in fees in transactions.

Motivation and Purposes
It hard to maintain the state of sponsorships database, lets use stateChangesById in the way you did for invoke script transactions.

Specification
Enhance GET /debug/stateChanges/info/{id} where sponsored asset is used for a fee to get stateChanges as how much WAVES was really paid in exchange for sponsored asset.

[pivoo81]

Hi Dmitry!
Ability to give such information is connected to storing additional data in the nodes DB. Which is not needed in most cases.
Maybe we implement it later with some optional node extension.

[deemru]

We already have:

waves.db.store-transactions-by-address = true
waves.db.store-invoke-script-results = true

Sponsored transactions for now are ok, but when you will implement WEP 2 it would be necessary to have this option.

[pivoo81]

We don't want to implement it in the Node, maybe it should be available in data-service, now thinking about it