Add dataProvider and update_time to Requisition (#217)

These are needed for measurement prober metric
(LastTerminalRequisitionTime) publication。

LastTerminalRequisitionTime, will have an attribute “data provider”
whose value is the name. The actual value of the metric will come from
the update time of the requisition that is associated with the
particular EDP for the most recently issued Measurement.

src/main/proto/wfa/measurement/api/v2alpha/BUILD.bazel

@@ -66,6 +66,7 @@ proto_library(
         "@com_google_googleapis//google/api:field_behavior_proto",
         "@com_google_googleapis//google/api:resource_proto",
         "@com_google_protobuf//:any_proto",
+        "@com_google_protobuf//:timestamp_proto",
     ],
 )
 

src/main/proto/wfa/measurement/api/v2alpha/requisition.proto

@@ -19,6 +19,7 @@ package wfa.measurement.api.v2alpha;
 import "google/api/field_behavior.proto";
 import "google/api/resource.proto";
 import "google/protobuf/any.proto";
+import "google/protobuf/timestamp.proto";
 import "wfa/measurement/api/v2alpha/crypto.proto";
 import "wfa/measurement/api/v2alpha/measurement.proto";
 import "wfa/measurement/api/v2alpha/protocol_config.proto";
@@ -259,4 +260,8 @@ message Requisition {
   // Denormalized `state` field from `measurement`.
   Measurement.State measurement_state = 13
       [(google.api.field_behavior) = OUTPUT_ONLY];
+
+  // When the 'Requisition' was last updated.
+  google.protobuf.Timestamp update_time = 16
+      [(google.api.field_behavior) = OUTPUT_ONLY];
 }