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/Dockerfile

@@ -1,5 +1,5 @@
 #### BUILDER IMAGE  ####
-FROM docker.io/node:14 as builder
+FROM docker.io/node:18 as builder
 LABEL maintainer="Chevdor <chevdor@gmail.com>"
 LABEL description="Substrate Telemetry Frontend builder image"
 
@@ -7,9 +7,7 @@ WORKDIR /opt/builder
 
 COPY . .
 
-RUN yarn install && \
-    yarn build && \
-    yarn cache clean
+RUN npm install && npm run build
 
 #### OUTPUT IMAGE ####
 FROM docker.io/nginx:stable-alpine