Add endpoint to clean up old index backups (#176)

* [ISSUE-172] Define delete old indexes backups endpoint

* Implementing delete index backup handler

* Create handler for deleting old resources

* Add tests for deleteIndexBackup operaton

* Cleanup code and fix failing build

* Use Java8 way of dealing with datetime, add tests of DeleteIndexBackupRequestHandler, small code tweaks

* Remove VersionedResourceObject.java which was renamed to VersioneResource.java

* Add multiple versioned resources with different creation dates in the DeleteBackupIndexHandler

* Regenerate grpc-gateway after changing DeleteIndexBackupResponse

* Change the logger string formatting

* Run spotlessapply to reformat code

clientlib/src/main/proto/yelp/nrtsearch/luceneserver.proto

@@ -232,6 +232,14 @@ service LuceneServer {
       body: "*"
     };
     }
+
+    rpc deleteIndexBackup (DeleteIndexBackupRequest) returns (DeleteIndexBackupResponse) {
+        option (google.api.http) = {
+            post: "/v1/delete_index_backup"
+            body: "*"
+        };
+    }
+
     /* Gets the state of a started index, includes settings, live_settings, search schema, suggest schema */
     rpc state (StateRequest) returns (StateResponse) {
         option (google.api.http) = {
@@ -743,6 +751,17 @@ message BackupIndexResponse {
     string metadataVersionHash = 2; //version identifier for metadata on s3
 }
 
+message DeleteIndexBackupRequest {
+    string indexName = 1; //name of the index to backup
+    string serviceName = 2; // remote storage namespace qualifier for service
+    string resourceName = 3; //remote storage namespace qualifier for resource e.g. indexName
+    int32 nDays = 4; //backups older than nDays will be deleted from s3
+}
+
+message DeleteIndexBackupResponse {
+    repeated string deletedVersionHashes = 1; // version hashes of backups which were deleted
+}
+
 message IndicesRequest {
 }