chore!: migrate package to ESM (#675)

This change transitions the package to be distributed as an ESM (ECMAScript Module)
instead of CommonJS. The main change is the output of ESM-compatible code by the
TypeScript compiler and the modification of the module type in `package.json`.

Given that most bundlers now support ESM-distributed packages, I decided to forgo
adding backward compatibility for CommonJS.

BREAKING CHANGE: The package is now distributed as an ESM module

.eslintrc.js → .eslintrc.cjs

@@ -1,5 +1,5 @@
 module.exports = {
-  extends: ['eslint:recommended', 'prettier', './eslint-typescript.js'],
+  extends: ['eslint:recommended', 'prettier', './eslint-typescript.cjs'],
   plugins: ['prettier', 'import'],
   env: {
     es6: true,

package.json

@@ -9,6 +9,7 @@
     "beach",
     "rx"
   ],
+  "type": "module",
   "company": "Ardoq AS",
   "homepage": "https://ardoq.github.io/rxbeach/",
   "bugs": "https://github.com/ardoq/rxbeach/issues",
@@ -46,7 +47,7 @@
     "test:unit-test": "yarn jest",
     "test:coverage": "yarn jest --config jest-coverage.config.mjs --rootDir .",
     "test:watch": "yarn test:unit-test --watch",
-    "lint": "yarn eslint --ext .ts src -c .eslintrc.js",
+    "lint": "yarn eslint --ext .ts src -c .eslintrc.cjs",
     "build": "rimraf dist && yarn tsc",
     "watch": "yarn tsc -w",
     "prepack": "yarn build -p tsconfig-publish.json",

tsconfig.json

@@ -14,7 +14,7 @@
 
     "outDir": "./dist",
     "declaration": true,
-    "module": "commonjs",
+    "module": "ESNext",
     "sourceMap": true
   },
   "include": ["src/**/*"]