SLO dashboard for ArgoCD

[lukaszgyg]

First of all thank you so much for the ArgoCD integration plugin, which we are using a lot in the last days!
The next step for the ArgoCD monitoring is for us to define SLOs. We believe that having good SLOs provides the highest-quality indication for when we need to take action in order to improve the service quality.
We identified metric argocd_app_reconcile as a good candidate for the service performance check. Maybe we should add the Datadog monitor definition which can be used for SLO dashboards?
Maybe you are planing to add other monitors for ArgoCD which can be used for the SLO dashboard.
Tagging @steveny91 and @fanny-jiang as you contributed a lot in to the ArgCD plugin and I would like to have your opinion here.