chore: add enumeration data type to .repo-metadata.json (#205)

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

.repo-metadata.json

@@ -1,16 +1,17 @@
 {
-  "name": "analytics-data",
-  "name_pretty": "Analytics Data",
-  "product_documentation": "https://developers.google.com/analytics/trusted-testing/analytics-data",
-  "api_description": "provides programmatic methods to access report data in Google Analytics App+Web properties.",
-  "client_documentation": "https://googleapis.dev/java/google-analytics-data/latest/index.html",
-  "release_level": "alpha",
-  "transport": "grpc",
-  "language": "java",
-  "repo": "googleapis/java-analytics-data",
-  "repo_short": "java-analytics-data",
-  "distribution_name": "com.google.analytics:google-analytics-data",
-  "api_id": "analytics-data.googleapis.com",
-  "requires_billing": true,
-  "codeowner_team": "@googleapis/analytics-dpe"
-}
+    "name": "analytics-data",
+    "name_pretty": "Analytics Data",
+    "product_documentation": "https://developers.google.com/analytics/trusted-testing/analytics-data",
+    "api_description": "provides programmatic methods to access report data in Google Analytics App+Web properties.",
+    "client_documentation": "https://googleapis.dev/java/google-analytics-data/latest/index.html",
+    "release_level": "alpha",
+    "transport": "grpc",
+    "language": "java",
+    "repo": "googleapis/java-analytics-data",
+    "repo_short": "java-analytics-data",
+    "distribution_name": "com.google.analytics:google-analytics-data",
+    "api_id": "analytics-data.googleapis.com",
+    "requires_billing": true,
+    "codeowner_team": "@googleapis/analytics-dpe",
+    "library_type": "GAPIC_AUTO"
+}