feat(docker, front): cleaner & more reproducible frontend

* The frontend dependencies are now cached in the docker images itself
* A little hack is used to restore them when needed ie: the `node_modules` folder is stored outside of the workdir and then brought in
* Images are now versioned on the registry
* The docker-compose file has been updated to use the new/versioned images.
* The documentation has been updated.
* And the Gitlab-CI has been tweaked.
Status Job ID Name Coverage
  Check
passed #498258
docker
check_back

00:00:22

passed #498259
docker
check_front

00:00:56

 
  Test
passed #498260
docker
test_back

00:00:58

93.0%
passed #498261
docker
test_frontend

00:01:24

 
  Lint
passed #498263
docker
eslint

00:00:21

passed #498262
docker
flake8

00:00:13

 
  Svg Gen Docu
passed #498264
docker
generate_UML_svg

00:00:15

 
  Documentation
passed #498265
docker
pages

00:00:12

 
  Deploy
passed pages:deploy

00:00:00