Use locksroot from TokenNetwork.ChannelSettled events

[pirapira]

Abstract

Now TokenNetwork.ChannelSettled() event contains locksroot of both participants. This issue keeps track of using these locksroot values in the client.

Motivation

If we do this, we do not have to look at the blockchain state for the locksroot values. This eases the state pruning problem.

Specification

Instead of asking onchain for locksroot values, use the locksroot values found in the SettleChannel() events.

Backwards Compatibility

This changes the state changes, so the databases will be broken. On raiden:develop we don't care about that.

[LefterisJP]

Hmmm since this is a breaking DB change, if we do it, it should be done before the mainnet release.

[palango]

There's already #4522 for that.

[LefterisJP]

Hmmm okay good to know this is already being worked on. But without a board entry it's hard to follow. I will add it there.

[LefterisJP]

Hmmm the assignment is wrong here. I wanted to assign Augusto. Rectifying.

[hackaugusto]

This is blocked by raiden-network/raiden-contracts#1176