Add Datadog Continuous Testing JSON schema (#4842)

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

Author: Drarig29

src/api/json/catalog.json

@@ -3394,6 +3394,12 @@
       ],
       "url": "https://www.krakend.io/schema/krakend.json"
     },
+    {
+      "name": "Datadog Continuous Testing",
+      "description": "Datadog Continuous Testing Configuration file",
+      "fileMatch": ["*.synthetics.json"],
+      "url": "https://raw.githubusercontent.com/DataDog/schema/main/datadog-ci/synthetics/test-config.schema.json"
+    },
     {
       "name": "Datadog Service Definition",
       "description": "Datadog Service Definition file",