[LukasHackl2]

This change updates the Debug UI breadcrumb implementation to use the reusable tree path breadcrumb API introduced in eclipse-platform/eclipse.platform.ui#4496.

The existing Debug UI breadcrumb implementation duplicated much of the generic breadcrumb viewer logic. With the new JFace implementation available, this PR:

• replaces the internal breadcrumb viewer with TreePathBreadcrumbViewer
• adapts the Debug-specific drop-down implementation to TreePathBreadcrumbDropDownSite
• keeps Debug-specific behavior in AbstractBreadcrumb, TreeViewerDropDown, and LaunchViewBreadcrumb
• removes the now duplicated internal breadcrumb item/viewer classes and their message bundle
• preserves persistent drop-down size settings in Debug UI

The Debug breadcrumb was tested at runtime after the migration and behaved as expected.

Depends on: eclipse-platform/eclipse.platform.ui#4496

[merks]

I assume that of course the build cannot work until the upstream platform.ui change is merged. I can try to pull both into my workspace...