support the open-icon of folder (#34168) (#34896)

Backport #34168 by @kerwin612

Co-authored-by: Kerwin Bryant <kerwin612@qq.com>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

modules/fileicon/entry.go

@@ -0,0 +1,31 @@
+// Copyright 2025 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package fileicon
+
+import "code.gitea.io/gitea/modules/git"
+
+type EntryInfo struct {
+	FullName      string
+	EntryMode     git.EntryMode
+	SymlinkToMode git.EntryMode
+	IsOpen        bool
+}
+
+func EntryInfoFromGitTreeEntry(gitEntry *git.TreeEntry) *EntryInfo {
+	ret := &EntryInfo{FullName: gitEntry.Name(), EntryMode: gitEntry.Mode()}
+	if gitEntry.IsLink() {
+		if te, err := gitEntry.FollowLink(); err == nil && te.IsDir() {
+			ret.SymlinkToMode = te.Mode()
+		}
+	}
+	return ret
+}
+
+func EntryInfoFolder() *EntryInfo {
+	return &EntryInfo{EntryMode: git.EntryModeTree}
+}
+
+func EntryInfoFolderOpen() *EntryInfo {
+	return &EntryInfo{EntryMode: git.EntryModeTree, IsOpen: true}
+}