Support filter with nested object in jsonpath expression

[fabricereix]

Following issue #420, add support for filter with nested in jsonpath expression.

for example

{
    "fruit": [
        {
            "name": "apple",
            "price": {
                "US": 100,
                "UN": 110
            }
        },
        {
            "name": "grape",
            "price": {
                "US": 200,
                "UN": 150
            }
        }
    ]
}

The jsonpath expression $.fruit[?(@.price.US==200)].name should return grape.

Note that this is implemented in jsonpath.com
but not described in the https://goessner.net/articles/JsonPath .