LDAP Refactoring to support syncronizing more than one user at a time. (#16705)

* Feature: add cron setting for the ldap settings

* Move ldap configuration read to special function

* Introduce cron setting (no docs for it yet, pending approval)

* Chore: duplicate ldap module as a service

* Feature: implement active sync

This is very early preliminary implementation of active sync.
There is only one thing that's going right for this code - it works.

Aside from that, there is no tests, error handling, docs, transactions,
it's very much duplicative and etc.

But this is the overall direction with architecture I'm going for

* Chore: introduce login service

* Chore: gradually switch to ldap service

* Chore: use new approach for auth_proxy

* Chore: use new approach along with refactoring

* Chore: use new ldap interface for auth_proxy

* Chore: improve auth_proxy and subsequently ldap

* Chore: more of the refactoring bits

* Chore: address comments from code review

* Chore: more refactoring stuff

* Chore: make linter happy

* Chore: add cron dep for grafana enterprise

* Chore: initialize config package var

* Chore: disable gosec for now

* Chore: update dependencies

* Chore: remove unused module

* Chore: address review comments

* Chore: make linter happy

pkg/setting/setting.go

@@ -869,14 +869,8 @@ func (cfg *Cfg) Load(args *CommandLineArgs) error {
 	analytics := iniFile.Section("analytics")
 	ReportingEnabled = analytics.Key("reporting_enabled").MustBool(true)
 	CheckForUpdates = analytics.Key("check_for_updates").MustBool(true)
-	GoogleAnalyticsId, err = valueAsString(analytics, "google_analytics_ua_id", "")
-	if err != nil {
-		return err
-	}
-	GoogleTagManagerId, err = valueAsString(analytics, "google_tag_manager_id", "")
-	if err != nil {
-		return err
-	}
+	GoogleAnalyticsId = analytics.Key("google_analytics_ua_id").String()
+	GoogleTagManagerId = analytics.Key("google_tag_manager_id").String()
 
 	alerting := iniFile.Section("alerting")
 	AlertingEnabled = alerting.Key("enabled").MustBool(true)