ES6 class convertion of LGraph (#63)

* LGraph ES6 class conversion

* Add compatibility to prototype extension

* Add jest test action

---------

Co-authored-by: filtered <176114999+webfiltered@users.noreply.github.com>

.github/workflows/test.yml

@@ -0,0 +1,30 @@
+name: Tests CI
+
+on:
+  push:
+    branches:
+      - main
+      - master
+      - 'dev*'
+  pull_request:
+    branches:
+      - main
+      - master
+      - 'dev*'
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    steps:
+    - name: Checkout
+      uses: actions/checkout@v4
+    - uses: actions/setup-node@v3
+      with:
+        node-version: lts/*
+    - name: Build
+      run: |
+        npm ci
+        npm run build
+    - name: Run jest tests
+      run: |
+        npm test -- --verbose