fix: redact sensitive information from logs

[moolen]

This PR redacts log output from the vault backend. The vault token and/or k8s jwt tokens are logged which shouldn't be the case.

[moolen]

What i did to test it:

Deploy the following es, start the application and observe the logs. There is no need to run a vault at all.

apiVersion: 'kubernetes-client.io/v1'
kind: ExternalSecret
metadata:
  name: vault
spec:
  backendType: vault
  vaultRole: my-vault-role
  kvVersion: 2 # defaults to 2
  data:
    - name: password
      key: secret/data/hello-service/password
      property: password
    - name: cert.p12
      key: secret/data/hello-service/certificates
      property: cert.p12
      isBinary: true # defaults to false

This is what's logged then:

{
   "level":50,
   "message_time":"2021-10-26T09:09:36.322Z",
   "pid":699618,
   "hostname":"inca",
   "payload":{
      "err":{
         "type":"RequestError",
         "message":"Error: connect ECONNREFUSED 127.0.0.1:8200",
         "stack":"...some stacktrace...",
         "name":"RequestError",
         "cause":{
            "type":"Error",
            "message":"connect ECONNREFUSED 127.0.0.1:8200",
            # ...
         },
         "error":{
            "type":"Error",
            "message":"connect ECONNREFUSED 127.0.0.1:8200",
            # ...
         },
         "options":{
            "json":{
               "role":"my-vault-role",
               "jwt":"[Redacted]" // <--- here
            },
            # ...
            "headers":"[Redacted]", // <--- headers are completely redacted
         }
      }
   },
   "msg":"failure while polling the secret default/vault"
}