Validate migration files (#18203)

JSON Schema validation for data used by Gitea during migrations

Discussion at https://forum.forgefriends.org/t/common-json-schema-for-repository-information/563

Co-authored-by: Loïc Dachary <loic@dachary.org>

cmd/restore_repo.go

@@ -43,6 +43,10 @@ var CmdRestoreRepository = cli.Command{
 			Usage: `Which items will be restored, one or more units should be separated as comma.
 wiki, issues, labels, releases, release_assets, milestones, pull_requests, comments are allowed. Empty means all units.`,
 		},
+		cli.BoolFlag{
+			Name:  "validation",
+			Usage: "Sanity check the content of the files before trying to load them",
+		},
 	},
 }
 
@@ -58,6 +62,7 @@ func runRestoreRepository(c *cli.Context) error {
 		c.String("owner_name"),
 		c.String("repo_name"),
 		c.StringSlice("units"),
+		c.Bool("validation"),
 	)
 	if statusCode == http.StatusOK {
 		return nil