Refactor embedded assets and drop unnecessary dependencies (#34692)

Benefits:

1. smaller binary size (reduces more than 1MB)
2. better control of the assets details
3. fewer unmaintained dependencies
4. faster startup if the assets are not needed
5. won't hang up editors when open "bindata.go" by accident

modules/timeutil/executable.go

@@ -1,50 +0,0 @@
-// Copyright 2022 The Gitea Authors. All rights reserved.
-// SPDX-License-Identifier: MIT
-
-package timeutil
-
-import (
-	"os"
-	"path/filepath"
-	"sync"
-	"time"
-
-	"code.gitea.io/gitea/modules/log"
-)
-
-var (
-	executablModTime     = time.Now()
-	executablModTimeOnce sync.Once
-)
-
-// GetExecutableModTime get executable file modified time of current process.
-func GetExecutableModTime() time.Time {
-	executablModTimeOnce.Do(func() {
-		exePath, err := os.Executable()
-		if err != nil {
-			log.Error("os.Executable: %v", err)
-			return
-		}
-
-		exePath, err = filepath.Abs(exePath)
-		if err != nil {
-			log.Error("filepath.Abs: %v", err)
-			return
-		}
-
-		exePath, err = filepath.EvalSymlinks(exePath)
-		if err != nil {
-			log.Error("filepath.EvalSymlinks: %v", err)
-			return
-		}
-
-		st, err := os.Stat(exePath)
-		if err != nil {
-			log.Error("os.Stat: %v", err)
-			return
-		}
-
-		executablModTime = st.ModTime()
-	})
-	return executablModTime
-}