Download bees-boot2-assembly JAR file with all dependencies

This module creates two things: (1) a text file that contains a list of GAV coordinates needed for the 2nd stage boot loader (2) jar files mentioned above, in the Maven repository directory layout. Using Maven repository directory layout, as opposed to more simpler "flat directory with full of jars", allow us to share the jar files between fallback bees-driver dependencies and boot2, which saves disk space a lot. We do this in a separate module outside boot2, so that the list includes the bees-boot2 jar itself.