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

frontend/tsconfig.json

@@ -1,9 +1,9 @@
 {
   "compilerOptions": {
     "baseUrl": ".",
-    "outDir": "build",
-    "module": "esnext",
-    "target": "ES2017",
+    "outDir": "./build/",
+    "module": "es2020",
+    "target": "es2015",
     "lib": [
       "dom",
       "dom.iterable",