Add asset symbol in snapshots export

[LefterisJP]

Abstract

In the snapshots we return the asset identifier and not the symbol. From a UX perspective returning the symbol in a different column is beneficial as the snapshot constitutes an account balance statement by a specific date and most accountans would not recognize what the identifier means, but would recognize DAI, USDT etc.

Task

Also add the symbol of the asset in the snapshot export

[LefterisJP]

This is finished by @dimyG here: #6463