Make rising sexps inside JSON literals work better

[Fuco1]

Think about the following cases:

• [ ] we might want to preserve the key and raise it one level up (DWIM?)

Depending on where the point is around address we might keep or remove the child label.

{
    method: 'POST',
    uri: config.uriRoot + '/SendData/v1',
    json: {
        signDate: context.happenedAt,
        address: {
            zipCode: context.postalcode,
            houseNumber: context.number,
        }        
    },
}

If before address, result should be replace parent

{
    method: 'POST',
    uri: config.uriRoot + '/SendData/v1',
    address: {
        zipCode: context.postalcode,
        houseNumber: context.number,
    },
}

(currently we get a line with json: address: { ...)

If after address result should be keep parent

{
    method: 'POST',
    uri: config.uriRoot + '/SendData/v1',
    json: {
        zipCode: context.postalcode,
        houseNumber: context.number,
    },
}

(this already works)

• [ ] If raising would bring us to top level we must always remove the key

example

{
    method: 'POST',
    uri: config.uriRoot + '/SendData/v1',
    json: {
        "SignDate": context.happenedAt,
        "Name": context.name,
        "ZipCode": context.postalcode,
        "HouseNumber": context.number
    }
}

We want to raise the json field to top level, so we should only keep the body and get rid of label so the result is always

{
    "SignDate": context.happenedAt,
    "Name": context.name,
    "ZipCode": context.postalcode,
    "HouseNumber": context.number
}

• [ ] make sure sp-splice-sexp-killing-around preserves the value after the key, it makes no sense to raise just the key.
• [ ] but make sure that if we're inside the value, the key is removed when doing sp-splice-sexp-killing-around
• [ ] It would be cool if this could also work inside strings in other languages. Maybe we could do some tentative parsing of a string literal and if it seems like a json, use json-read-from-string and then DTRT.