Calculate IPNI ContextID for Filecoin StorageMarket deals
See #1 (comment):
It turns out that Boost computes the Context ID from market.ClientDealProposal containing two fields: Proposal and ClientSignature (source code, see also the screenshot below).
Unfortunately, the data provided in StateMarketDeals.json.zst by Glif (presumably a snapshot of Lotus’ method StateMarketDeals) contains only the Proposal but not the ClientSignature.
