OpenSea renamed the field `supply`, which used to be required, to
`total_supply`. Fixes the error:

`undefined is not an object (evaluating 'contract.supply.toString')`

Which prevented some NFTs from loading. A more accurate `total_supply`
was also added to the collection object, which is now preferred to the
one on the contract.

1. Import a wallet containing NFTs on mainnet
2. Enable NFT autodetection in settings, verify the NFTs appear
3. Verify descriptions, collection/token images are correct

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