[MM-53454] Add export file settings + slash command for public link (#23915)

Co-authored-by: Mattermost Build <build@mattermost.com>

server/cmd/mmctl/client/client.go

@@ -146,5 +146,6 @@ type Client interface {
 	ListExports(ctx context.Context) ([]string, *model.Response, error)
 	DeleteExport(ctx context.Context, name string) (*model.Response, error)
 	DownloadExport(ctx context.Context, name string, wr io.Writer, offset int64) (int64, *model.Response, error)
+	GeneratePresignedURL(ctx context.Context, name string) (*model.PresignURLResponse, *model.Response, error)
 	ResetSamlAuthDataToEmail(ctx context.Context, includeDeleted bool, dryRun bool, userIDs []string) (int64, *model.Response, error)
 }