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/api/admin.go

@@ -12,7 +12,7 @@ import (
 func AdminGetSettings(c *m.ReqContext) {
 	settings := make(map[string]interface{})
 
-	for _, section := range setting.Cfg.Sections() {
+	for _, section := range setting.Raw.Sections() {
 		jsonSec := make(map[string]interface{})
 		settings[section.Name()] = jsonSec