[asset manager] Use signal backed API endpoints to build view showing asset hierarchy/graph

[miltonhultgren]

As a PoC, we would like to build a new view that uses the Assets API in order to experiment with what is possible and what the performance of that view would be like with the signal backed endpoints.

We have two ideas we could try, rather than using the common list/table layout, perhaps:

1. One could show multiple kinds of assets in a card layout but with layers/hierarchy (a stack). Each layer would be an asset kind and the relationships are part of the visual vertical flow (services, below that containers that run those services, below that the pods and hosts that support those containers). It may be good to make each card as similar visually as possible since they are each an asset, but perhaps have some dedicated area to show asset specific information such as metrics or alerts.
2. One could show an actual graph with nodes and edges, with some color coding for metric health or alert count. Perhaps as a stretch it could be possible to pivot to other assets to find more nodes to add to the graph.

Since we currently only have 4 kinds of assets both views will be limited in the scope they can render.

The common thing for both views is that they need a starting point or some shared concept such as "assets belonging to namespace X". Perhaps if one starts from the "lower" level assets like a host, the view should render in a bottom-to-top direction (host -> pod -> container -> service), while if one enters from a "higher" level like service it should render top-to-bottom. It could be possible to link to this view from the Host or Service inventories.

AC

TBD

[elasticmachine]

Pinging @elastic/observability-asset-management (Team:Observed Asset Management)