Bug 123496 [IDE] Use operation validation API for IDE actions
We should use the Resources/Core operation validation API in the IDE actions for manipulating resources.
bundles/org.eclipse.ui.ide/extensions/org/eclipse/ui/actions/CopyFilesAndFoldersOperation.java
* <p>
	 * Note this method is for internal use only. It is not API.
	 * </p>
	 * 
	 * @param destination
	 *            the destination container
	 * @param sourceResources
	 *            the source resources
	 * @return an error message, or <code>null</code> if the path is valid
	 */
	public String validateDestination(IContainer destination,
			IResource[] sourceResources) {
		if (!isAccessible(destination)) {
			return IDEWorkbenchMessages.CopyFilesAndFoldersOperation_destinationAccessError;
		}
		String destinationMessage = validateDestinationLocation(destination);
		if (destinationMessage != null) {
			return destinationMessage;
		}
		IContainer firstParent = null;
		IPath destinationLocation = destination.getLocation();
		for (int i = 0; i < sourceResources.length; i++) {
			IResource sourceResource = sourceResources[i];
			if (firstParent == null) {
				firstParent = sourceResource.getParent();
			} else if (firstParent.equals(sourceResource.getParent()) == false) {
				
				return IDEWorkbenchMessages.CopyFilesAndFoldersOperation_parentNotEqual;
			}
			IPath sourceLocation = sourceResource.getLocation();