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>

modules/setting/cron.go

@@ -7,7 +7,11 @@ import "reflect"
 
 // GetCronSettings maps the cron subsection to the provided config
 func GetCronSettings(name string, config interface{}) (interface{}, error) {
-	if err := Cfg.Section("cron." + name).MapTo(config); err != nil {
+	return getCronSettings(CfgProvider, name, config)
+}
+
+func getCronSettings(rootCfg ConfigProvider, name string, config interface{}) (interface{}, error) {
+	if err := rootCfg.Section("cron." + name).MapTo(config); err != nil {
 		return config, err
 	}
 
@@ -18,7 +22,7 @@ func GetCronSettings(name string, config interface{}) (interface{}, error) {
 		field := val.Field(i)
 		tpField := typ.Field(i)
 		if tpField.Type.Kind() == reflect.Struct && tpField.Anonymous {
-			if err := Cfg.Section("cron." + name).MapTo(field.Addr().Interface()); err != nil {
+			if err := rootCfg.Section("cron." + name).MapTo(field.Addr().Interface()); err != nil {
 				return config, err
 			}
 		}