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/session.go

@@ -15,7 +15,8 @@ import (
 
 // SessionConfig defines Session settings
 var SessionConfig = struct {
-	Provider string
+	OriginalProvider string
+	Provider         string
 	// Provider configuration, it's corresponding to provider.
 	ProviderConfig string
 	// Cookie name to save session ID. Default is "MacaronSession".
@@ -39,8 +40,8 @@ var SessionConfig = struct {
 	SameSite:    http.SameSiteLaxMode,
 }
 
-func newSessionService() {
-	sec := Cfg.Section("session")
+func loadSessionFrom(rootCfg ConfigProvider) {
+	sec := rootCfg.Section("session")
 	SessionConfig.Provider = sec.Key("PROVIDER").In("memory",
 		[]string{"memory", "file", "redis", "mysql", "postgres", "couchbase", "memcache", "db"})
 	SessionConfig.ProviderConfig = strings.Trim(sec.Key("PROVIDER_CONFIG").MustString(path.Join(AppDataPath, "sessions")), "\" ")
@@ -67,6 +68,7 @@ func newSessionService() {
 		log.Fatal("Can't shadow session config: %v", err)
 	}
 	SessionConfig.ProviderConfig = string(shadowConfig)
+	SessionConfig.OriginalProvider = SessionConfig.Provider
 	SessionConfig.Provider = "VirtualSession"
 
 	log.Info("Session Service Enabled")