New field 'body' to HTTP GET/GET-by-POST metadata

[guicassolato]

It adds a new field spec.metadata.body.

The new field is an alternative to spec.metadata.bodyParameters for defining raw HTTP bodies and ensure proper content encoding of JSON with multiple levels.

E.g., the following config:

apiVersion: authorino.kuadrant.io/v1beta1
kind: AuthConfig
metadata:
  name: talker-api-protection
spec:
  hosts: ["talker-api-authorino.127.0.0.1.nip.io"]
  metadata:
  - name: echo-api-post-json
    http:
      endpoint: http://talker-api.default.svc.cluster.local:3000/metadata?encoding=json
      method: POST
      contentType: application/json
      body:
        valueFrom:
          authJSON: |
            \{"original_path":"{context.request.http.headers.x-forwarded-for}","request":\{"key1":\{"key2":\{"key3":"{context.request.http.headers.x-forwarded-for}"\}\}\}\}

will send a request:

POST /metadata?encoding=json HTTP/1.1
Content-Length: 81
Content-Type: application/json
Host: talker-api.default.svc.cluster.local:3000
User-Agent: Go-http-client/1.1
Accept-Encoding: gzip
Version: HTTP/1.1
(…request headers omitted)

{"original_path":"10.244.0.8","request":{"key1":{"key2":{"key3":"10.244.0.8"}}}}

A similar config to the above using bodyParameters instead would be:

kubectl apply -f -<<EOF
apiVersion: authorino.kuadrant.io/v1beta1
kind: AuthConfig
metadata:
  name: talker-api-protection
spec:
  hosts: ["talker-api-authorino.127.0.0.1.nip.io"]
  metadata:
  - name: echo-api-post-json
    http:
      endpoint: http://talker-api.default.svc.cluster.local:3000/metadata?encoding=json
      method: POST
      contentType: application/json
      bodyParameters:
      - name: original_path
        valueFrom: { authJSON: context.request.http.headers.x-forwarded-for }
      - name: request
        valueFrom:
          authJSON: |
            \{"key1":\{"key2":\{"key3":"{context.request.http.headers.x-forwarded-for}"\}\}\}

In the latter however, 'request' is encoded as a JSON string, thus resulting in the following request sent to the metadata service:

POST /metadata?encoding=json HTTP/1.1
Content-Length: 92
Content-Type: application/json
Host: talker-api.default.svc.cluster.local:3000
User-Agent: Go-http-client/1.1
Accept-Encoding: gzip
Version: HTTP/1.1
(…request headers omitted)

{"original_path":"10.244.0.8","request":"{\"key1\":{\"key2\":{\"key3\":\"10.244.0.8\"}}}\n"}

Closes #271