feat: switch from npm to yarn (#500)

* feat: switch from npm to yarn

* fix: build

* fix: replace yarn run with yarn

* fix: nodejs version install in Docker image

* fix: initialize mobx state

Co-authored-by: Karol Sójko <karolsojko@gmail.com>

app/assets/javascripts/tsconfig.json

@@ -1,6 +1,6 @@
 {
   "compilerOptions": {
-    "target": "esnext",
+    "target": "ES2019",
     "module": "commonjs",
     "moduleResolution": "node",
     "allowJs": true,