Auth: Set the default org after User login (#83918)

* poc

* add logger, skip hook when user is not assigned to default org

* Add tests, move to hook folder

* docs

* Skip for OrgId < 1

* Address feedback

* Update docs/sources/setup-grafana/configure-grafana/_index.md

* lint

* Move the hook to org_sync.go

* Update pkg/services/authn/authnimpl/sync/org_sync.go

* Handle the case when GetUserOrgList returns error

---------

Co-authored-by: Christopher Moyer <35463610+chri2547@users.noreply.github.com>
Co-authored-by: Karl Persson <kalle.persson@grafana.com>

pkg/setting/setting.go

@@ -411,6 +411,7 @@ type Cfg struct {
 	AutoAssignOrg              bool
 	AutoAssignOrgId            int
 	AutoAssignOrgRole          string
+	LoginDefaultOrgId          int64
 	OAuthSkipOrgRoleUpdateSync bool
 
 	// ExpressionsEnabled specifies whether expressions are enabled.
@@ -1658,6 +1659,7 @@ func readUserSettings(iniFile *ini.File, cfg *Cfg) error {
 	cfg.AllowUserOrgCreate = users.Key("allow_org_create").MustBool(true)
 	cfg.AutoAssignOrg = users.Key("auto_assign_org").MustBool(true)
 	cfg.AutoAssignOrgId = users.Key("auto_assign_org_id").MustInt(1)
+	cfg.LoginDefaultOrgId = users.Key("login_default_org_id").MustInt64(-1)
 	cfg.AutoAssignOrgRole = users.Key("auto_assign_org_role").In(
 		string(roletype.RoleViewer), []string{
 			string(roletype.RoleNone),