improved transaction flows

[adecaro]

Currently the token-sdk services relay implicitly on the commit pipeline of the backend to update various internal data structure.
This Issue calls for the reduction of this dependency.
Here are the tasks envisioned:

• finality should relay on the token-sdk's dbs. (new finality based on local dbs #593)
• transaction status in the dbs should contain also a message to better understand why a given transaction has been considered invalid (support for transaction status message #596, enhanced commit pipelines (fabric and orion) fabric-smart-client#539)
• refactor FSC fabric platform (fabric refactor fabric-smart-client#543)
• Add TransactionFilter to both fabric and orion commit pipeline to process specific transactions even if they are unknown (register transaction filter #611)
• The translation of the token request for fabric and orion should contain the hash of the token request to later be checked again the local copy (store token request hash in rwsets #597).
• Rename SubscribeTxStatusChanges to FinalityListener. It should have the following contract: If the transaction is already Valid or Invalid, the listener is called immediately.
• FinalityListener should pass also a transaction reference as an array of bytes. This reference will contain the hash of the token request that was committed.
• The token db should be updated when the transaction status of ttxdb changes to Confirmed. (append tokens on finality event #598)
• the token transaction lifecycle should not require the distribution also the actual transaction sent to the backend. Indeed, this transaction might not be available. (updated vault's DiscardTx function behaviour fabric-smart-client#566, remove envelope #625)

[adecaro]

Done