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_test.go

@@ -10,7 +10,7 @@ import (
 	ini "gopkg.in/ini.v1"
 )
 
-func Test_GetCronSettings(t *testing.T) {
+func Test_getCronSettings(t *testing.T) {
 	type BaseStruct struct {
 		Base   bool
 		Second string
@@ -27,7 +27,8 @@ Base = true
 Second = white rabbit
 Extend = true
 `
-	Cfg, _ = ini.Load([]byte(iniStr))
+	cfg, err := ini.Load([]byte(iniStr))
+	assert.NoError(t, err)
 
 	extended := &Extended{
 		BaseStruct: BaseStruct{
@@ -35,8 +36,7 @@ Extend = true
 		},
 	}
 
-	_, err := GetCronSettings("test", extended)
-
+	_, err = getCronSettings(cfg, "test", extended)
 	assert.NoError(t, err)
 	assert.True(t, extended.Base)
 	assert.EqualValues(t, extended.Second, "white rabbit")