Initial Baby Step to refactoring settings from global vars to instance (#11777)

* wip: start on refactoring settings

* settings: progress on settings refactor

* refactor: progress on settings refactoring

* fix: fixed failing test

* settings: moved smtp settings from global to instance

pkg/social/social.go

@@ -58,7 +58,7 @@ func NewOAuthService() {
 	allOauthes := []string{"github", "google", "generic_oauth", "grafananet", "grafana_com"}
 
 	for _, name := range allOauthes {
-		sec := setting.Cfg.Section("auth." + name)
+		sec := setting.Raw.Section("auth." + name)
 		info := &setting.OAuthInfo{
 			ClientId:       sec.Key("client_id").String(),
 			ClientSecret:   sec.Key("client_secret").String(),