Make the Backend fully ESM compatible, remove Babel (#1332)

* First step towards making Backend fully ESM-compatible:
- Necessary changes made in package.json
- Most other changes are due to a missing file extension in most imports.
- One small change was that __dirname isn't available when using ESM, so I changed the way we resolve path to the YAML specifications by using process.cwd(), as we do in other fs.* functions.
- I'm testing the VSCode-GitHub integration now, hence the branch name that does not follow our convention - sorry

* Removed Babel, etc:
- Removed Babel, including: 'compile' step in package.json and other commands, all dependencies and configuration file
- Replaced the 'compile' step with a basic copy of directory to dist/. The reasoning behind this is that it let's us continue using current Dockerfiles etc without any changes.
- Major cleanups in ESlint config. Seems good so far, check out the screenshot in this issue: https://github.com/hajkmap/Hajk/issues/1328\#issuecomment-1517542129
- Moved Prettier's config to an own file
- Prettier seems fine too, see screenshot above
- If this works as intended, we have a much cleaner toolchain. NodeJS 16+ is now required but it shouldn't be a major problem.

* Added missing definition, no idea how it got lost.

* New lock file after clean deps install. Should close #1328.

* Workaround the fact that __dirname isn't available in ESM. This pretty much closes #1328.

* Ensure that the OpenApiValidator runs _after_ any async routes have been imported:
- This was discovered in #1332 but the problem first came up in #1309.
- OAV will only take care of routes that exists when the middleware runs. Hence, any async imports that haven't yet run will be unknown to the OAV and render a 404.
- This ugly setTimeout fix takes care of it but I'm open for a better solution (including discussing the future of OAV in our Backend).

* Minor fix in Prettier config to reflect that we use LF for new line throughout the project.

new-backend/.eslintrc.json

@@ -1,33 +1,11 @@
 {
-  "parser": "@babel/eslint-parser",
-  "parserOptions": {
-    "sourceType": "module",
-    "requireConfigFile": false
-  },
-  "extends": [
-    "eslint:recommended",
-    "plugin:node/recommended",
-    "plugin:prettier/recommended"
-  ],
   "env": {
-    "mocha": true,
-    "node": true
+    "es2022": true,
+    "node": true,
+    "mocha": true
   },
-  "plugins": ["prettier", "node"],
-  "rules": {
-    "no-unused-vars": 2,
-    "node/no-unsupported-features/es-syntax": 0,
-    "node/no-unpublished-import": ["off"],
-    "prettier/prettier": [
-      "error",
-      {
-        "singleQuote": false,
-        "trailingComma": "es5",
-        "bracketSpacing": true,
-        "jsxBracketSameLine": true,
-        "printWidth": 80,
-        "endOfLine": "auto"
-      }
-    ]
+  "extends": "eslint:recommended",
+  "parserOptions": {
+    "sourceType": "module"
   }
 }

new-backend/.prettierrc

@@ -0,0 +1,9 @@
+{
+  "tabWidth": 2,
+  "useTabs": false,
+  "singleQuote": false,
+  "trailingComma": "es5",
+  "bracketSpacing": true,
+  "printWidth": 80,
+  "endOfLine": "lf"
+}