[GLA Analytics] Add support for additional Google Listings & Ads analytics fields

[ThomazFB]

We should ensure we can handle requesting and storing any campaign analytics fields:

• Endpoint: GET /wc/gla/ads/reports/programs
• Argument: fields: Limit totals to the provided fields (sales, spend, clicks, impressions, and/or conversions) — we should be able to request any of these fields and store the response.
• Sample response with all fields:

{
    "campaigns": [
        {
            "id": 123,
            "name": "One",
            "status": "enabled",
            "subtotals": {
                "sales": 11,
                "spend": 63.14,
                "clicks": 139,
                "impressions": 16037,
                "conversions": 3
            }
        },
        {
            "id": 234,
            "name": "Two",
            "status": "enabled",
            "subtotals": {
                "sales": 0,
                "spend": 9.87,
                "clicks": 15,
                "impressions": 901,
                "conversions": 0
            }
        }
    ],
    "intervals": [
        {
            "interval": "2021-09",
            "subtotals": {
                "sales": 0,
                "spend": 38,
                "clicks": 90,
                "impressions": 9941,
                "conversions": 0
            }
        },
        {
            "interval": "2021-10",
            "subtotals": {
                "sales": 11,
                "spend": 35.01,
                "clicks": 64,
                "impressions": 6997,
                "conversions": 3
            }
        }
    ],
    "totals": {
        "sales": 11,
        "spend": 73.01,
        "clicks": 154,
        "impressions": 16938,
        "conversions": 3
    }
}

[dangermattic]

Thanks for reporting! 👍