Add GetUptimeByKey to store interface

storage/store/memory/util_bench_test.go

@@ -4,13 +4,14 @@ import (
 	"testing"
 
 	"github.com/TwinProduction/gatus/core"
-	"github.com/TwinProduction/gatus/storage/store/paging"
+	"github.com/TwinProduction/gatus/storage/store/common"
+	"github.com/TwinProduction/gatus/storage/store/common/paging"
 )
 
 func BenchmarkShallowCopyServiceStatus(b *testing.B) {
 	service := &testService
 	serviceStatus := core.NewServiceStatus(service.Key(), service.Group, service.Name)
-	for i := 0; i < core.MaximumNumberOfResults; i++ {
+	for i := 0; i < common.MaximumNumberOfResults; i++ {
 		AddResult(serviceStatus, &testSuccessfulResult)
 	}
 	for n := 0; n < b.N; n++ {