feat: Add swap metric to fly-apps dashboard

[shortdiv]

Adding a swap metric to fly apps dashboard so we can link it to the ui

Related to https://github.com/superfly/ui-ex/pull/1020

[wjordan]

We already display swap in the Memory - Detailed panel on the Fly Instance dashboard. It uses a matcher with a regex on Swap.* to apply a transform to the negative Y axis so it can be viewed alongside normal memory usage. (This is similar to how it's displayed in the Node Exporter Full dashboard).

I could see adding swap in a similar way on the negative Y axis to the "Memory Utilization" panel in the Fly App dashboard, perhaps with a >0 on the query so the time series doesn't show up when swap isn't enabled. I think a separate swap-only panel like is a bit more noisy and would be inconsistent with the existing swap metrics in the Fly Instance memory panel.

[shortdiv]

I think I understood what you meant, updated!