Prepend default imports for injected Groovy language

[mlytvyn]

Adding standard imports in ImpEx according to docs: https://help.sap.com/docs/SAP_COMMERCE_CLOUD_PUBLIC_CLOUD/aa417173fe4a4ba5a473c93eb730a417/640172cbde9149ab8eb818180544020a.html?locale=en-US

import de.hybris.platform.core.*
import de.hybris.platform.core.model.user.* 
import de.hybris.platform.core.HybrisEnumValue
import de.hybris.platform.util.* 
import de.hybris.platform.impex.jalo.* 
import de.hybris.platform.jalo.*
import de.hybris.platform.jalo.c2l.Currency
import de.hybris.platform.jalo.c2l.* 
import de.hybris.platform.jalo.user.*
import de.hybris.platform.jalo.flexiblesearch.* 
import de.hybris.platform.jalo.product.ProductManager