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.

Trace BundleGroupComponent and its use by the About dialog, Welcome action, and Tips and Tricks action, then inspect the deprecated IPlatformConfiguration and IPlatformConfigurationFactory dependency. Compare the required feature id, version, branding bundle, about.ini, and feature.xml data with the proposed dedicated provider. Done means those consumers use the new provider and BundleGroupComponent is removed without relying on the deprecated API.

Written by the indexing model from the issue text.