chore: add enumeration data type to .repo-metadata.json (#441)

Adds a standard enumeration of library types in .repo-metadata.json

.repo-metadata.json

@@ -1,16 +1,17 @@
 {
-  "name": "container",
-  "name_pretty": "Kubernetes Engine",
-  "product_documentation": "https://cloud.google.com/kubernetes-engine/",
-  "client_documentation": "https://googleapis.dev/java/google-cloud-container/latest/",
-  "issue_tracker": "https://issuetracker.google.com/savedsearches/559777",
-  "release_level": "ga",
-  "language": "java",
-  "repo": "googleapis/java-container",
-  "repo_short": "java-container",
-  "distribution_name": "com.google.cloud:google-cloud-container",
-  "codeowner_team": "@googleapis/cicd",
-  "api_id": "container.googleapis.com",
-  "api_description": "is an enterprise-grade platform for containerized applications, including stateful and stateless, AI and ML, Linux and Windows, complex and simple web apps, API, and backend services. Leverage industry-first features like four-way auto-scaling and no-stress management. Optimize GPU and TPU provisioning, use integrated developer tools, and get multi-cluster support from SREs.",
-  "transport": "grpc"
+    "name": "container",
+    "name_pretty": "Kubernetes Engine",
+    "product_documentation": "https://cloud.google.com/kubernetes-engine/",
+    "client_documentation": "https://googleapis.dev/java/google-cloud-container/latest/",
+    "issue_tracker": "https://issuetracker.google.com/savedsearches/559777",
+    "release_level": "ga",
+    "language": "java",
+    "repo": "googleapis/java-container",
+    "repo_short": "java-container",
+    "distribution_name": "com.google.cloud:google-cloud-container",
+    "codeowner_team": "@googleapis/cicd",
+    "api_id": "container.googleapis.com",
+    "api_description": "is an enterprise-grade platform for containerized applications, including stateful and stateless, AI and ML, Linux and Windows, complex and simple web apps, API, and backend services. Leverage industry-first features like four-way auto-scaling and no-stress management. Optimize GPU and TPU provisioning, use integrated developer tools, and get multi-cluster support from SREs.",
+    "transport": "grpc",
+    "library_type": "GAPIC_AUTO"
 }