New BatchLiquidator optimized for L2 rollups

[ngmachado]

Use the new BatchLiquidator contract: superfluid-finance/protocol-monorepo#1306
reduces cost on L2s.

• add to ethereum-contracts package and update the dependency here (this was blocked by the npm package release which is blocked by a subgraph re-indexing to finish, not waiting for it any longer)
• always use the batch interface (instead of host interface) on L2s (even if batch size is 1)
• deploy to all mainnets, and update metadata dependency

[d10r]

results on Optimism:
1 liquidation via host: 6350 L1 gas
1 liquidation via new batch: 4900 L1 gas
2 liquidations via new batch: 6200 L1 gas
2 liquidations via old batch: 7000 L1 gas
9 liquidations via new batch: 11400 L1 gas

We could further optimize the cost for popular SuperTokens by deploying BatchLiquidator contracts specific to them, such that the SuperToken address can also be omitted from calldata. Could be implemented in a way similar to how canonical SuperToken wrappers were done in SuperTokenFactory.

[d10r]

@ngmachado please check if you can simplify liquidator.js - merge singleTerminations() and sendBatch() into one function.
Also revisit the terminology as discussed. Now there's work, batch, , batchWork, termination, liquidations.
Can probably be simplified to less terms, also reusing a term in plural form for lists/arrays of it.