Update frontend build system to shed old dependencies, and address fallout from that (#521)

* get tests working and update copyright headers

* lint fix

* eslint ts update

* update CI to use NPM

* fix CI

* prettier

* npm, not yarn for docker

* remove unused package

* bump dockerfile to latest node LTS and no need for cache clean

* make frontend Dockerfile work and remove unused SUBSTRATE_TELEMETRY_SAMPLE

* remove final yarn references

* add another comment

* remove unused import

* remove more unused deps

* comment typo

.github/workflows/frontend.yml

@@ -35,14 +35,14 @@ jobs:
       with:
         node-version: ${{ matrix.node-version }}
 
-    - name: install
-      run: yarn install
+    - name: Install
+      run: npm install
 
-    - name: check
-      run: yarn pretty:check
+    - name: Check
+      run: npm run pretty:check
 
     - name: Test
-      run: yarn test
+      run: npm run test
 
     - name: Build
-      run: yarn build
+      run: npm run build