Provide IBundleGroupProvider from a dedicated bundle instead of org.eclipse.update.configurator

IPlatformConfiguration and IPlatformConfigurationFactory are marked @Deprecated(forRemoval = true, since = "2025-06 (removal in 2027-06 or later)").

The only thing still depending on them outside org.eclipse.update.configurator is BundleGroupComponent.
The About dialog, the Welcome action and the Tips and Tricks action are wired to an implementation with a removal date. When that date arrives, removing the API silently empties the About dialog's feature list.

It is also expensive. Getting bundle groups from it builds PlatformConfiguration, which reconciles the install site and opens every plug-in jar on the UI thread during startup, several seconds on large installations. The data actually needed (feature id, version, branding bundle, plus about.ini and feature.xml content) never requires opening a jar.

Proposal: register an equivalent provider from a new small bundle reading only feature metadata, and delete BundleGroupComponent. org.eclipse.update.configurator itself stays until the announced removal.

Verfolge BundleGroupComponent und seine Verwendung durch den About-Dialog, die Welcome-Aktion und die Tips and Tricks-Aktion, und untersuche anschließend die Abhängigkeit von der veralteten IPlatformConfiguration und IPlatformConfigurationFactory. Vergleiche die erforderlichen Daten zu Feature-ID, Version, Branding-Bundle, about.ini und feature.xml mit dem vorgeschlagenen dedizierten Provider. Als erledigt gilt die Aufgabe, wenn diese Consumer den neuen Provider verwenden und BundleGroupComponent entfernt ist, ohne von der veralteten API abhängig zu sein.

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