[APM] Service maps: Explore optionally exchanging the service node popover for a flyout-type details panel

[formgeist]

Summary of the problem (If there are multiple problems or use cases, prioritize them) Since we're aiming at adding more information to the details of the node, we want to explore a way to create more space for visualizing metrics and adding more information about the service (i.e. health / alerts and more). Additionally, the popovers currently close when the user interacts with the map, so it's not possible to compare i.e. one node and then explore more of the map in the meantime.

[elasticmachine]

Pinging @elastic/observability-design (design)

[smith]

This might be good but we're not currently planning on implementing it.