Add workflow to build, test, and check formatting/artifacts on PR (#8)

* add workflow

* add workflow and remove husky

* prettier tests

.github/workflows/checkin.yml

@@ -0,0 +1,28 @@
+name: "PR Checks"
+on: [pull_request, push]
+
+jobs:
+  check_pr:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v1
+
+    - name: "npm ci"
+      run: npm ci
+
+    - name: "npm run build"
+      run: npm run build
+
+    - name: "npm run test"
+      run: npm run test
+
+    - name: "check format"
+      run: npm run format-check
+
+    - name: "check for uncommitted changes"
+      # Ensure no changes, but ignore node_modules dir since dev/fresh ci deps installed.
+      run: |
+        git diff --exit-code --stat -- . ':!node_modules' \
+        || (echo "##[error] found changed files after build. please 'npm run build && npm run format'" \
+                 "and check in all changes" \
+            && exit 1)