[presign] Explorer: Status for pre-signing

[alfetopito]

Summary

1. Add new order status: signature pending
2. Potentially refactor how status are loaded to use API responses instead of calculating them locally

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Context:

@anxolin @W3stside @alfetopito

Just pinging you guys so you are aware of the new order status (for an order that was accepted by the orderbook and is waiting for the on-chain presignature).

Originally posted by @nlordell in gnosis/gp-v2-services#1025 (comment)

[nlordell]

Just as an update, the new status was renamed to presignaturePending.

[anxolin]

Not sure if we would like to do this, but maybe is nice to see in the explorer the signing method too: ie. ethsign, eip712, pre-sign, ...

Being a explorer for the protocol, make sense to expose all the protocol info relative to the order. Not sure if there should be some hidden fields and this belong there. Adding now pre-sign orders, maybe is interesting to add this too

[alfetopito]

I agree, but I think this is a different task.

I would also want to have what you mentioned today: show & decode appData, loading ipfs data if any