Add new command to create "dependency-downloading bootstrapper jar"

[jk-1]

Current mill foo.assembly creates a fat jar that is big but can be run without network access.

Scala-cli has command package which creates smaller "lightweight launcher jar" or "dependency-downloading bootstrapper jar". This will need network access as it downloads missing jars before launching the actual application.

Please implement this scala-cli type of package command into mill also. More discussion about this is here