feat: add Docker build (#41187)

* feat(docker): build and use client and api images

* feat: always use .env

dotenv fails without throwing if the .env file is missing and never
overwrites variables if they already exist. As such, we can use it in
build pipelines.

* fix: remove quotes from env vars

dotenv normalises quoted and unquoted strings (X=x, X='x' and
X="x") all become the same .env object {X: 'x'}. However, Docker's
env_file does not (the three cases are distinct).  As a result, we
should use unquoted strings for consistency.

* fix: provide custom warning when .env is missing

* feat(docker): include client-config

* fix(docker): remove build packages from api image

* fix(docker): run script from correct dir

* fix(docker): correct permissions and dests

* fix(docker): consolidate run steps

This is standard practice, but did not have a noticable affect on the
image size

* fix(docker): clean the npm cache

Prior to this step the image was 1.11GB uncompressed and we got a modest
saving, 1.09GB after.

* refactor(docker): regexless COPY directives

* feat(docker): use alpine

This shrinks the image down to 259MB

* fix(docker): update build scripts

* fix: correct the server Dockerfile RUNs

* DEBUG: expose mysql port for seeding

* chore: update client Dockerfile's node versions

* fix: remove executable permissions from index.js

It's not a cli, so I don't think it needs to be executable.

* chore: update node and remove stale comments

* feat: use ENTRYPOINT + CMD to allow runtime config

* fix: add CURRICULUM_LOCALE arg

* feat: allow client port configuration

* feat: allow api port to be configured

* refactor: use unique variable names for ports

* fix: add default CLIENT_PORT

* refactor: clean up

api-server/src/server/index.js

@@ -32,7 +32,7 @@ Rx.config.longStackSupport = process.env.NODE_DEBUG !== 'production';
 const app = loopback();
 
 app.set('state namespace', '__fcc__');
-app.set('port', process.env.PORT || 3000);
+app.set('port', process.env.API_PORT || 3000);
 app.set('views', path.join(__dirname, 'views'));
 app.use(loopback.token());
 app.use(