move stackgl parts into stackgl_modules folder

 - import and export those required in plotly.js
 - pre-bundle stackgl/gl-vis modules using node16
 - test npm ci using npm v6 and cibuild with node12

Author: archmoj

Diff for: .circleci/config.yml

@@ -10,7 +10,23 @@ orbs:
 # https://hub.docker.com/r/cimg/node/tags/
 
 jobs:
-  install-and-cibuild:
+  install-and-cibuild-node12: # cibuild using node 12 & npm 6
+    docker:
+      - image: cimg/node:12.22.7
+    working_directory: ~/plotly.js
+    steps:
+      - checkout
+      - run:
+          name: Set up build environment
+          command: .circleci/env_build.sh
+      - run:
+          name: Pretest
+          command: npm run pretest
+      - run:
+          name: CI-Build
+          command: npm run cibuild
+
+  install-and-cibuild: # main cibuild using node 16 & npm 7
     docker:
       - image: cimg/node:16.8.0
     working_directory: ~/plotly.js
@@ -370,6 +386,8 @@ workflows:
   version: 2
   build-and-test:
     jobs:
+      - install-and-cibuild-node12
+
       - install-and-cibuild
       - timezone-jasmine:
           requires:

Diff for: .eslintignore

@@ -1,3 +1,4 @@
+stackgl_modules
 node_modules
 dist
 build