Fix Project Explorer not refreshing source containers after drag-and-drop move

[Copilot]

Fixes eclipse-platform#3525. When moving files between projects via drag-and-drop, the file appeared in both source and destination instead of being removed from source.

Changes

• ResourceDropAdapterAssistant.handleDrop(): Added refresh of source containers after move operations (excludes copy/link operations)
• ResourceDropAdapterAssistant.handlePluginTransferDrop(): Added refresh of source containers for consistency

Implementation

After the existing target container refresh, iterate through moved resources and refresh their parent containers:

// Refresh source containers to ensure they update in the UI
for (IResource resource : resources) {
    IContainer parent = resource.getParent();
    if (parent != null && parent.isAccessible() && !parent.equals(target)) {
        parent.refreshLocal(IResource.DEPTH_ONE, null);
    }
}

The target was already being refreshed, but source containers were not, causing stale UI state.

Original prompt

Fix eclipse-platform#3525

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