* [APM] Runtime service maps

* Make nodes interactive

* Don't use smaller range query on initial request

* Address feedback from Ron

* Get all services separately

* Get single service as well

* Query both transactions/spans for initial request

* Optimize 'top' query for service maps

* Use agent.name from scripted metric

* adds basic loading overlay

* filter out service map node self reference edges from being rendered

* Make service map initial load time range configurable with
`xpack.apm.serviceMapInitialTimeRange` default to last 1 hour in
milliseconds

* ensure destination.address is not missing in the composite agg when
fetching sample trace ids

* wip: added incremental data fetch & progress bar

* implement progressive loading design while blocking service map interaction during loading

* adds filter that destination.address exists before fetching sample trace ids

* reduce pairs of connections to 1 bi-directional connection with arrows on both ends of the edge

* Optimize query; add update button

* Allow user interaction after 5s, auto update in that time, otherwise
show toast for user to update the map with button

* Correctly reduce nodes/connections

* - remove non-interactive state while loading
- use cytoscape element definition types

* - readability improvements to the ServiceMap component
- only show the update map button toast after last request loads

* addresses feedback for changes to the Cytoscape component

* Add span.type/span.subtype do external nodes

* PR feedback

Co-authored-by: Dario Gieselaar <d.gieselaar@gmail.com>