Add lab on new module system

[WeeknightMVP]

This lab describes Cryptol's new module system, which has not yet been merged. To test it requires a workspace in which one can build Cryptol from source and access different Git branches. With these prerequisites, assuming cryptol-course and cryptol-specs are cloned or downloaded to the same directory, the following should work:

$ cd ~/workspace  # or whatever
$ git clone https://github.com/GaloisInc/cryptol
$ git clone https://github.com/GaloisInc/cryptol-specs
$ git clone https://github.com/weaversa/cryptol-course
$ cd cryptol-course
$ git switch new-module-system
$ cd ../cryptol
$ git switch functors-merge
$ ./cry build
...
$ CRYPTOLPATH=../cryptol-course:../cryptol-specs ./cry run
Cryptol> :m labs::NewModuleSystem::NewModuleSystemAnswers
labs::NewModuleSystem::NewModuleSystemAnswers>

[WeeknightMVP]

We should turn off CI for this branch until functors-merge is merged.

[WeeknightMVP]

This PR proposes tweaking the suggested lab order for the overall course, swapping in a Module System landing page that comprises two labs: our existing lab for basic Parameterized Modules around the Simon/Speck block ciphers, and another for Cryptol 3's New Module System (interfaces, submodules, etc.) around block cipher modes. Key Wrapping becomes an optional (but strongly recommended) lab to weave most of the concepts taught in the course in preparation for the Capstone.

[WeeknightMVP]

On second thought, we should keep Key Wrapping in the recommended path, as Capstone uses material from it and key wrapping is an important concept.