Torque: Implement a DSL for CSA

An overview of motivation behind Torque and some of its principles
can be found here: https://bit.ly/2qAI5Ep

Note that there is quite a bit of work left to do in order to get
Torque production-ready for any non-trivial amount of code, but
landing the prototype as-is will allow for much faster iteration.

Bugs will be filed for all of the big-ticket items that are not
landing blockers but called out in this patch as important to fix.

Cq-Include-Trybots: luci.v8.try:v8_linux_nosnap_rel;luci.v8.try:v8_linux_noi18n_rel_ng
Change-Id: Ib07af70966d5133dc57344928885478b9c6b8b73
Reviewed-on: https://chromium-review.googlesource.com/845682


Commit-Queue: Daniel Clifford <danno@chromium.org>
Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#52618}