Test Call Hierarchy Viewlet

[jrieken]

Refs: #83274, #83419

• Windows @eamodio
• macOS @JacksonKearl

Complexity: 3

In addition to "Peek Call Hierarchy" there is now also "Show Call Hierarchy". Use a sample call hierarchy extension, like https://github.com/jrieken/demo-callhierarchy or https://github.com/microsoft/vscode-extension-samples/tree/master/call-hierarchy-sample and test that:

• the context menu has 'Peek > Peek Call Hierarchy' and 'Show Call Hierarchy'
• the viewlet and peek view show the same data
• the viewlet uses the same space as Find All References and Find All Implementations
• the viewlet has a unified history for all "data sources"
• call hierarchy results are highlighted in the editor when active
• the viewlet allows to toggle the "directions" (caller of vs. calls from)
• the viewlet allows to restart itself at any node