ApproachSettlement may refer to entities without MarketID

[Athanasius]

e.g.

2022-02-17 20:11:55,201 - ERROR - Gateway:274: Failed Validation "[<ValidationError: "'MarketID' is a required property">]" (404, "E:D Market Connector [Windows]", "5.3.0", "https://eddn.edcd.io/schemas/approachsettlement/1", "-")

One possibility is visitor beacons. I'll confirm that shortly.

As such we will want to at least document that Senders should check for this and not send when MarketID is not set.

However...

Proposal

Allow approachsettlement/1 messages without MarketID so as to support data about visitor beacons. Listeners should be check for if MarketID is present or not and react accordingly.

[Athanasius]

NB: Might also get the 'no MarketID' form from approaching things like "Ancient Ruins".

[Athanasius]

Confirmed that visitor beacons trigger the event without MarketID:

{ "timestamp":"2022-02-18T14:33:35Z", "event":"ApproachSettlement", "Name":"Battlegroup's Disappearance", "SystemAddress":1109989017963, "BodyID":8, "BodyName":"Alioth 1 a", "Latitude":59.972752, "Longitude":-84.506294 }

[Athanasius]

Currently 'installations' don't appear to trigger an ApproachSettlement event. For https://eddb.io/attraction/59944, "Strategic Statistical Services" in Alioth around Alioth 3 C A, this is the only event in that Journal:

{ "timestamp":"2022-02-18T14:31:21Z", "event":"FSSSignalDiscovered", "SystemAddress":1109989017963, "SignalName":"Strategic Statistical Services" }

[Athanasius]

Also affects Ancient Ruins, per Bravada Cadelanne @ EDCD #eddn:

{ "timestamp":"2022-02-18T15:02:04Z", "event":"ApproachSettlement", "Name":"$Ancient:#index=1;", "Name_Localised":"Ancient Ruins (1)", "SystemAddress":3515254557027, "BodyID":13, "BodyName":"Synuefe XR-H d11-102 1 b", "Latitude":-46.576923, "Longitude":133.985107 }

[klightspeed]

Ancient Ruins (Odyssey):

{
    "timestamp": "2022-02-18T15:02:04Z",
    "event": "ApproachSettlement",
    "Name": "$Ancient:#index=1;",
    "Name_Localised": "Ancient Ruins (1)",
    "SystemAddress": 3515254557027,
    "BodyID": 13,
    "BodyName": "Synuefe XR-H d11-102 1 b",
    "Latitude": -46.576923,
    "Longitude": 133.985107
}

Ancient Ruins (Horizons):

{
    "timestamp": "2022-02-18T15:06:45Z",
    "event": "ApproachSettlement",
    "Name": "$Ancient:#index=1;",
    "Name_Localised": "Ancient Ruins (1)",
    "SystemAddress": 3515254557027,
    "BodyID": 13,
    "BodyName": "Synuefe XR-H d11-102 1 b",
    "Latitude": -31.788902,
    "Longitude": -128.941498
}

[Athanasius]

This has now been addressed in live code (went directly into develop and onwards).

77a2d41