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/lfs.go

@@ -25,22 +25,22 @@ var LFS = struct {
 	Storage
 }{}
 
-func newLFSService() {
-	sec := Cfg.Section("server")
+func loadLFSFrom(rootCfg ConfigProvider) {
+	sec := rootCfg.Section("server")
 	if err := sec.MapTo(&LFS); err != nil {
 		log.Fatal("Failed to map LFS settings: %v", err)
 	}
 
-	lfsSec := Cfg.Section("lfs")
+	lfsSec := rootCfg.Section("lfs")
 	storageType := lfsSec.Key("STORAGE_TYPE").MustString("")
 
 	// Specifically default PATH to LFS_CONTENT_PATH
 	// FIXME: DEPRECATED to be removed in v1.18.0
-	deprecatedSetting("server", "LFS_CONTENT_PATH", "lfs", "PATH")
+	deprecatedSetting(rootCfg, "server", "LFS_CONTENT_PATH", "lfs", "PATH")
 	lfsSec.Key("PATH").MustString(
 		sec.Key("LFS_CONTENT_PATH").String())
 
-	LFS.Storage = getStorage("lfs", storageType, lfsSec)
+	LFS.Storage = getStorage(rootCfg, "lfs", storageType, lfsSec)
 
 	// Rest of LFS service settings
 	if LFS.LocksPagingNum == 0 {