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>

cmd/doctor.go

@@ -87,14 +87,16 @@ func runRecreateTable(ctx *cli.Context) error {
 	golog.SetPrefix("")
 	golog.SetOutput(log.NewLoggerAsWriter("INFO", log.GetLogger(log.DEFAULT)))
 
-	setting.LoadFromExisting()
-	setting.InitDBConfig()
+	setting.InitProviderFromExistingFile()
+	setting.LoadCommonSettings()
+	setting.LoadDBSetting()
 
-	setting.EnableXORMLog = ctx.Bool("debug")
+	setting.Log.EnableXORMLog = ctx.Bool("debug")
 	setting.Database.LogSQL = ctx.Bool("debug")
-	setting.Cfg.Section("log").Key("XORM").SetValue(",")
+	// FIXME: don't use CfgProvider directly
+	setting.CfgProvider.Section("log").Key("XORM").SetValue(",")
 
-	setting.NewXORMLogService(!ctx.Bool("debug"))
+	setting.InitSQLLog(!ctx.Bool("debug"))
 	stdCtx, cancel := installSignals()
 	defer cancel()