feat: Add ElectricityMaps support

[rossf7]

Towards #27

[rossf7]

Here is an example of the data. The Electricity Maps forecast is 24 hours with data in hourly increments.

https://static.electricitymaps.com/api/docs/index.html#forecasted-carbon-intensity

kubectl -n kube-system get configmap carbon-intensity -o json | jq -r '.binaryData["data"]' | base64 -D | jq . | head -n 30
[
  {
    "location": "westus",
    "timestamp": "2023-08-22T13:00:00Z",
    "duration": 60,
    "value": 340
  },
  {
    "location": "westus",
    "timestamp": "2023-08-22T14:00:00Z",
    "duration": 60,
    "value": 333
  },
  {
    "location": "westus",
    "timestamp": "2023-08-22T15:00:00Z",
    "duration": 60,
    "value": 286
  },
  {
    "location": "westus",
    "timestamp": "2023-08-22T16:00:00Z",
    "duration": 60,
    "value": 260
  },
  {
    "location": "westus",
    "timestamp": "2023-08-22T17:00:00Z",
    "duration": 60,
    "value": 248
...

[pauldotyu]

This looks great to me! Thanks @rossf7 for your contribution!

[helayoty]

LGTM many thanks for your contribution @rossf7