chore: add typescript typechecking

Author: drazisil-codecov

.eslintrc

@@ -0,0 +1,18 @@
+module.exports = {
+  root: true,
+  parser: '@typescript-eslint/parser',
+  plugins: ['@typescript-eslint'],
+  extends: ['eslint:recommended', 'plugin:@typescript-eslint/recommended'],
+  parserOptions: {
+    ecmaVersion: 9,
+  },
+  env: {
+    es6: true,
+    jest: true,
+    node: true,
+    'shared-node-browser': true,
+  },
+  rules: {
+    '@typescript-eslint/no-var-requires': 1,
+  },
+}