provide grafana dashboard for cloudflared and others

[STRRL]

trafficstars

I found that there is no comprehensive grafana dashboard for cloudflare tunnel.

I think we could provide our own one.

reference:

• https://grafana.com/grafana/dashboards/17457-cloudflare-tunnels-cloudflared/
• https://developers.cloudflare.com/cloudflare-one/connections/connect-networks/monitor-tunnels/metrics/