Refactor the setting to make unit test easier (#22405)

Some bugs caused by less unit tests in fundamental packages. This PR
refactor `setting` package so that create a unit test will be easier
than before.

- All `LoadFromXXX` files has been splited as two functions, one is
`InitProviderFromXXX` and `LoadCommonSettings`. The first functions will
only include the code to create or new a ini file. The second function
will load common settings.
- It also renames all functions in setting from `newXXXService` to
`loadXXXSetting` or `loadXXXFrom` to make the function name less
confusing.
- Move `XORMLog` to `SQLLog` because it's a better name for that.

Maybe we should finally move these `loadXXXSetting` into the `XXXInit`
function? Any idea?

---------

Co-authored-by: 6543 <6543@obermui.de>
Co-authored-by: delvh <dev.lh@web.de>

routers/install/setting.go

@@ -15,20 +15,21 @@ import (
 
 // PreloadSettings preloads the configuration to check if we need to run install
 func PreloadSettings(ctx context.Context) bool {
-	setting.LoadAllowEmpty()
+	setting.InitProviderAllowEmpty()
+	setting.LoadCommonSettings()
 	if !setting.InstallLock {
 		log.Info("AppPath: %s", setting.AppPath)
 		log.Info("AppWorkPath: %s", setting.AppWorkPath)
 		log.Info("Custom path: %s", setting.CustomPath)
-		log.Info("Log path: %s", setting.LogRootPath)
+		log.Info("Log path: %s", setting.Log.RootPath)
 		log.Info("Configuration file: %s", setting.CustomConf)
 		log.Info("Prepare to run install page")
 		translation.InitLocales(ctx)
 		if setting.EnableSQLite3 {
 			log.Info("SQLite3 is supported")
 		}
-		setting.InitDBConfig()
-		setting.NewServicesForInstall()
+
+		setting.LoadSettingsForInstall()
 		svg.Init()
 	}
 
@@ -37,8 +38,9 @@ func PreloadSettings(ctx context.Context) bool {
 
 // reloadSettings reloads the existing settings and starts up the database
 func reloadSettings(ctx context.Context) {
-	setting.LoadFromExisting()
-	setting.InitDBConfig()
+	setting.InitProviderFromExistingFile()
+	setting.LoadCommonSettings()
+	setting.LoadDBSetting()
 	if setting.InstallLock {
 		if err := common.InitDBEngine(ctx); err == nil {
 			log.Info("ORM engine initialization successful!")