Add buying/selling pkid to GetAllDAOCoinLimitOrders with tests

[diamondhands0]

This PR contains a few SAFE modifications to support the launch of DeSo AMMs and CCV2:

• Make _getDAOCoinLimitOrderEntry public so we can call it on a UtxoView from backend.
• Add buyingCoinPkid *PKID and sellingCoinPkid *PKID to the call signature of GetAllDAOCoinLimitOrdersForThisTransactor. This allows you to get all the transactions for a particular transactor by market. Note that this change is SAFE because if you pass (nil, nil) for the new arguments then the behavior is identical to what it was previously. So it gives us the new functionality without any risk or any new indexes.
• Add new tests for GetAllDAOCoinLimitOrdersForThisTransactor to make sure the new arguments actually work and upgrade old tests.
• Add a public IsDeleted for DAOCoinLimitOrderEntry. This is needed to support filtering out unconfirmed orders in the backend, which is something new we added.

[lazynina]

• #1276
• #1275 👈
• feature/proof-of-stake

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