Add a extra config to Statuscake provider

[matthijswolters-rl]

The config options that have been added are:

• Raw POST data
• User Agent string
  The statuscake API docs defining these config options can be found here: https://developers.statuscake.com/api/#tag/uptime/operation/create-uptime-test

How to test:

1. run a local kubernetes cluster and set KUBECONFIG to the correct kubeconfig
2. run make install in repo dir
3. run the local docker registry docker run -d -p 5000:5000 --name registry registry:2
4. build the image and push it

• docker build -t localhost:5000/controller:latest .
• docker push localhost:5000/controller:latest

5. add the secret imc-config and test-secret and the endpoint monitor (ask me for the commands)
6. run make deploy
7. edit the deployment in ingressmonitorcontroller-system to use the image localhost:5000/controller:latest
8. kill the pod so it pulls the most recent version