Make Web UI build handle alloy i18n resources dynamic loading

In order to address ELEMENTS-835, our alloy editor import script will have to dynamically load i18n resources for the alloy editor. We need to make sure our gulp script will include them and the path to the location of where they are deployed in the war is properly updated at build time.

Note this is only needed for 9.10 and 10.10.

New build after polymer 3 migration will handle that out of the box.