Only build jscoq (+ addons) in Docker phase.

Still, both don't fully work, needs more research as to witness what's
broken.

Hopefully this fixes #278

- Migrated patches for 8.14.
- Up wacoq to 8.14 in docker image
- install: 8.14 requires `coq-core` and `coq-stdlib` to be installed.
- Set version 0.14.0.

This still requires considerable work, but when ready it should
solve parts of #69 and #121.

As for now, we don't push the image to a registry yet; we ought to
decide:

- when to build the docker image [maybe only on main branches]
- where to push it
- what to include
- a standard setup for addons CI, so they pull the image and then
  build and publish their own package
- how this does integrate with npm, maybe we shouldn't push the image
  but just a npm package built using docker [so addons do get the
  correct binaries to push to npm too]

Based on:

https://github.com/marketplace/actions/build-and-push-docker-images

This is just a basic building setup, for linux at the moment.

Github Actions is way more powerful than travis, so we can improve
many previous things of the setup, concretely:

- re-add OSX build
- generate a docker image
- set a job for each addon, or create a push event so addons are built
  on their own repos

Closes #224

Thanks to Jason Gross for the help with the SerAPI action.