make it exit gracefully. (#8101)

* make it exit gracefully.

* add kig message

* git update error code

* exit with error code

* exit with 0

* Update server/start.go

Co-authored-by: SaReN <sahithnarahari@gmail.com>
Co-authored-by: Alessio Treglia <alessio@tendermint.com>

server/start.go

@@ -115,7 +115,13 @@ which accepts a path for the resulting pprof file.
 
 			// amino is needed here for backwards compatibility of REST routes
 			err := startInProcess(serverCtx, clientCtx, appCreator)
+			errCode, ok := err.(ErrorCode)
+			if !ok {
 				return err
+			}
+
+			serverCtx.Logger.Debug(fmt.Sprintf("received quit signal: %d", errCode.Code))
+			return nil
 		},
 	}