Expose a retrieval-deal filter similar ( if not identical ) to the storage-filter

[ribasushi]

Miners need ability to reject retrieval deals based on an external hook just like they can do for storage deals today:

lotus/node/builder.go

Line 463 in 2bf42d5

Override(new(dtypes.DealFilter), modules.BasicDealFilter(dealfilter.CliDealFilter(cfg.Dealmaking.Filter))),

If possible - the same Filter=... config option should be reused, and the JSON fed to the program can have an extra identifier "this is a storage deal" / "this is a retrieval deal".

At present the storage-deal `Filter` program receives the following as input:
expand

{
  "Proposal": {
    "PieceCID": {
      "/": "baga6ea4seaqkszyboqhhsakpcpesq7xptojhacvewgde3hykipl7e2idqukboky"
    },
    "PieceSize": 134217728,
    "VerifiedDeal": false,
    "Client": "t1kxd4qebtvwx6bn6a4ypc3afiwmdhsabtppdmwxi",
    "Provider": "t01013",
    "Label": "mAXCg5AIgPjcct4EJGoUpVyBp1LNS+nObc+wuAm0JLEbRR9RnNeM",
    "StartEpoch": 7664,
    "EndEpoch": 528705,
    "StoragePricePerEpoch": "62500000",
    "ProviderCollateral": "270047582",
    "ClientCollateral": "0"
  },
  "ClientSignature": {
    "Type": 1,
    "Data": "U6b7DMxGAunm3+P8gi7efmS8ecnsTAKc8sGjRYS0UHhX/TupXLH93CDngqEcUQce2Zkyb5AT3Y963cJgVyoW3QE="
  },
  "ProposalCid": {
    "/": "bafyreihtud3iumsm4dyio3bu3sstj6w5lfs5wucoiikisyjpqe4yl63rwq"
  },
  "AddFundsCid": null,
  "PublishCid": null,
  "Miner": "12D3KooWGdpXeqJbLEUyJp4o1GvLVxzoGiYGKiYUq6LB5r8f1vF4",
  "Client": "12D3KooWSRvagorF8HSaraZRpXWq4JpjrfJfa6kQ22kv8wnxztRF",
  "State": 15,
  "PiecePath": "",
  "MetadataPath": "",
  "SlashEpoch": 0,
  "FastRetrieval": true,
  "Message": "",
  "StoreID": 2,
  "FundsReserved": "0",
  "Ref": {
    "TransferType": "graphsync",
    "Root": {
      "/": "bafykbzacea7dohfxqeervbjjk4qgtvftkl5hhg3t5qxae3ijfrdncr6um426g"
    },
    "PieceCid": null,
    "PieceSize": 0
  },
  "AvailableForRetrieval": false,
  "DealID": 0,
  "CreationTime": "2020-10-01T15:58:00.157336467Z"
}

Its exit code is being evaluated here:

lotus/markets/dealfilter/cli.go

Lines 25 to 37 in 2bf42d5

	c := exec.Command("sh", "-c", cmd)
	c.Stdin = bytes.NewReader(j)
	c.Stdout = &out
	c.Stderr = &out
	switch err := c.Run().(type) {
	case nil:
	return true, "", nil
	case *exec.ExitError:
	return false, out.String(), nil
	default:
	return false, "filter cmd run error", err
	}