[#13004] Add Timestamp to Tag list API (#13026)

* Add Timestamp to Tag list API

* Add unit test for ToCommitMeta

* Rename timestamp to created

* Reformat files

modules/structs/repo_commit.go

@@ -20,6 +20,8 @@ type Identity struct {
 type CommitMeta struct {
 	URL string `json:"url"`
 	SHA string `json:"sha"`
+	// swagger:strfmt date-time
+	Created time.Time `json:"created"`
 }
 
 // CommitUser contains information of a user in the context of a commit.