add Exchange locked funds data in subgraph #975
Description
until now, the funds are managed at the entity level, to get the amount of funds that has been deposited in the protocol by each entity, and how much can be withdrawn.
In order to give a better understanding about the protocol mechanism, it seems relevant to provide a service to record how much funds is locked (in escrow) at an exchange level.
This would include: seller deposit, item price, dr fee, etc...
This change would allow to give any observer a better overview about the funds management for each exchange