Add ESLint and Prettier

.eslintrc.yml

@@ -0,0 +1,13 @@
+root: true
+parser: '@typescript-eslint/parser'
+plugins: ['@typescript-eslint']
+extends:
+  - eslint:recommended
+  - plugin:@typescript-eslint/eslint-recommended
+  - plugin:@typescript-eslint/recommended
+  - prettier/@typescript-eslint
+rules:
+  # '@typescript-eslint/explicit-function-return-type': 0
+  '@typescript-eslint/no-use-before-define':
+    - 2
+    - functions: false