POPL22 Pipe AEC Artifact

This is the artifact for the POPL22 AEC submission #39: Safe, Modular Packet Pipeline Programming, slightly modified based on responses from the AEC. To begin, download and unzip the folder anywhere (On a non-Mac machine, ignore the _MACOSX folder and just use the lucid subfolder). Further instructions are included in the readme.md file inside, which can also be viewed here: https://github.com/PrincetonUniversity/lucid/tree/popl22_artifact. The online readme file is slightly newer, addressing a few bugs we have found in the VM when it is hosted on a Windows computer. To avoid these, we recommend hosting the VM on a Mac.