Resolve "Implement gNMI subscription management"

Description

Related Issue

Motivation and Context

How Has This Been Tested?

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.

Related to #382

api/proto/gosdn/subscriptionmanagement/subscriptionmanagement.proto

@@ -27,6 +27,10 @@ service SubscriptionManagementService {
             body: "*"
         };
     }
+
+    rpc ResetAllSubscriptions(ResetAllSubscriptionsRequest) returns (ResetAllSubscriptionsResponse) {
+        option (google.api.http) = {get: "/submanagement/reset"};
+    }
 }
 
 message Subscription{
@@ -81,3 +85,11 @@ message AddRequest{
 message AddResponse{
     int64 timestamp = 1;
 }
+
+message ResetAllSubscriptionsRequest {
+    int64 timestamp = 1;
+}
+
+message ResetAllSubscriptionsResponse {
+    int64 timestamp = 1;
+}