:pencil: added formatting and style rules for eslint and prettier

backend/.eslintrc

@@ -0,0 +1,32 @@
+{
+    "env": {
+        "browser": true,
+        "commonjs": true,
+        "es2021": true
+    },
+    "extends": [
+        "eslint:recommended",
+        "prettier"
+    ],
+    "parserOptions": {
+        "ecmaVersion": 12
+    },
+    "rules": {
+        "indent": [
+            "error",
+            4
+        ],
+        "linebreak-style": [
+            "error",
+            "unix"
+        ],
+        "quotes": [
+            "error",
+            "single"
+        ],
+        "semi": [
+            "error",
+            "never"
+        ]
+    }
+}

backend/.prettierrc

@@ -0,0 +1,6 @@
+trailingComma: "all"
+tabWidth: 4
+semi: false
+singleQuote: true
+bracketSpacing: true
+arrowParens: "avoid"