allow users to filter STAC items by properties during the execution of load_collection

[leotizzei]

connection.load_collection(
    "SENTINEL2_L2A",
    ...,
    max_cloud_cover=80,
)

or

connection.load_collection(
    "SENTINEL1_GRD",
    ...,
    properties={
        "relativeOrbitNumber": lambda x: x==116
    },
)

this section describes this functionality