message: Group DPSCertificate->List with other operations
  * fixing relative paths to definitons and commondefinitions.json
  * Update iotdps.json
  "operationId": "DpsCertificates_List", -> "operationId": "DpsCertificate_List", so the list operation is grouped with the others on docs
diff: "tags": [
  "GET"
  ],
  - "operationId": "DpsCertificates_List",
  + "operationId": "DpsCertificate_List",
  "description": "Get all the certificates tied to the provisioning service.",
  "x-ms-examples": {
  "DPSGetCertificates": { "$ref": "./examples/DPSGetCertificates.json" }
  