Reduce duplicate and useless code in options (#23369)

Avoid maintaining two copies of code, some functions can be used with
both `bindata` and `no bindata`.

And removed `GetRepoInitFile`, it's useless now.
`Readme`/`Gitignore`/`License`/`Labels` will clean the name and use
custom files when available.

modules/options/base.go

@@ -7,11 +7,52 @@ import (
 	"fmt"
 	"io/fs"
 	"os"
+	"path"
 	"path/filepath"
 
+	"code.gitea.io/gitea/modules/setting"
 	"code.gitea.io/gitea/modules/util"
 )
 
+// Locale reads the content of a specific locale from static/bindata or custom path.
+func Locale(name string) ([]byte, error) {
+	return fileFromDir(path.Join("locale", path.Clean("/"+name)))
+}
+
+// Readme reads the content of a specific readme from static/bindata or custom path.
+func Readme(name string) ([]byte, error) {
+	return fileFromDir(path.Join("readme", path.Clean("/"+name)))
+}
+
+// Gitignore reads the content of a gitignore locale from static/bindata or custom path.
+func Gitignore(name string) ([]byte, error) {
+	return fileFromDir(path.Join("gitignore", path.Clean("/"+name)))
+}
+
+// License reads the content of a specific license from static/bindata or custom path.
+func License(name string) ([]byte, error) {
+	return fileFromDir(path.Join("license", path.Clean("/"+name)))
+}
+
+// Labels reads the content of a specific labels from static/bindata or custom path.
+func Labels(name string) ([]byte, error) {
+	return fileFromDir(path.Join("label", path.Clean("/"+name)))
+}
+
+// WalkLocales reads the content of a specific locale
+func WalkLocales(callback func(path, name string, d fs.DirEntry, err error) error) error {
+	if IsDynamic() {
+		if err := walkAssetDir(filepath.Join(setting.StaticRootPath, "options", "locale"), callback); err != nil && !os.IsNotExist(err) {
+			return fmt.Errorf("failed to walk locales. Error: %w", err)
+		}
+	}
+
+	if err := walkAssetDir(filepath.Join(setting.CustomPath, "options", "locale"), callback); err != nil && !os.IsNotExist(err) {
+		return fmt.Errorf("failed to walk locales. Error: %w", err)
+	}
+	return nil
+}
+
 func walkAssetDir(root string, callback func(path, name string, d fs.DirEntry, err error) error) error {
 	if err := filepath.WalkDir(root, func(path string, d fs.DirEntry, err error) error {
 		// name is the path relative to the root
@@ -37,3 +78,18 @@ func walkAssetDir(root string, callback func(path, name string, d fs.DirEntry, e
 	}
 	return nil
 }
+
+func statDirIfExist(dir string) ([]string, error) {
+	isDir, err := util.IsDir(dir)
+	if err != nil {
+		return nil, fmt.Errorf("unable to check if static directory %s is a directory. %w", dir, err)
+	}
+	if !isDir {
+		return nil, nil
+	}
+	files, err := util.StatDir(dir, true)
+	if err != nil {
+		return nil, fmt.Errorf("unable to read directory %q. %w", dir, err)
+	}
+	return files, nil
+}