[6/N] feat(gateway): add queue request listing

api/submitqueue/gateway/proto/gateway.proto

@@ -124,6 +124,28 @@ message GetRequestSummaryByChangeURIResponse {
     repeated RequestSummary requests = 1;
 }
 
+// ListRequest defines one bounded queue receipt-history query.
+message ListRequest {
+    // Exact queue to query.
+    string queue = 1;
+    // Inclusive lower receipt-time bound in Unix milliseconds.
+    int64 received_at_or_after_ms = 2;
+    // Exclusive upper receipt-time bound in Unix milliseconds.
+    int64 received_before_ms = 3;
+    // Maximum results to return. Zero selects the server default; values above the server maximum are invalid.
+    int32 page_size = 4;
+    // Opaque continuation token from a previous response. Empty selects the first page.
+    string page_token = 5;
+}
+
+// ListResponse defines one page of queue receipt history.
+message ListResponse {
+    // Requests ordered by receipt time descending, then sqid descending.
+    repeated RequestSummary requests = 1;
+    // Opaque continuation token. Empty when this is the last page.
+    string next_page_token = 2;
+}
+
 // ***************
 // Error messages, returned as `google.rpc.Status` messages.
 // ***************
@@ -184,4 +206,7 @@ service SubmitQueueGateway {
     // GetRequestSummaryByChangeURI returns current materialized statuses for an exact pinned change URI.
     rpc GetRequestSummaryByChangeURI(GetRequestSummaryByChangeURIRequest) returns (GetRequestSummaryByChangeURIResponse) {}
 
+    // List returns requests received for one queue during a bounded receipt-time range.
+    rpc List(ListRequest) returns (ListResponse) {}
+
 }