EMP: view function to determine bid outcome

[0xJem]

The frontend and SDK integrators would benefit from an on-chain method to determine if a bid resulted in a payout, refund or both (e.g. partial fill).

We could do this in two ways:

• Add a view function to EMP.sol (and BatchAuctionModule?) that returns the outcome given a lotId and bidId
• Add a view function to a new contract, EmpCatalogue.sol, that returns the same

[0xJem]

This is implemented in the following manner:

• getBidClaim on BatchAuctionModule, implemented in EncryptedMarginalPrice.
• Abstracted the code to calculate the bid claim into an internal function, now shared by _claimBid() and getBidClaim().
• This enables a caller to determine the outcome of a specific bid