[APM] Add 'View traces in Discover' button to Service Map edge popover

[miloszmarcinkowski]

Summary

Add a "View traces" button to the Service Map edge popover so users can explore requests between services/dependencies in Discover.

Changes

• Add "View traces" outlined button (with Discover icon) to the service map edge popover, matching existing popover button styles
• Build Discover link filtered by source service name and destination service name
• Pass active kuery, environment, rangeFrom and rangeTo to the Discover link
• Add unit tests

[elasticmachine]

Pinging @elastic/obs-presentation-team (Team:obs-presentation)