chore: add code formatting and linting (#952)

.stylelintrc

@@ -0,0 +1,14 @@
+{
+  "processors": ["stylelint-processor-styled-components"],
+  "extends": [
+    "stylelint-config-recommended",
+    "stylelint-config-styled-components"
+  ],
+  "rules": {
+    "block-no-empty": null,
+    "no-duplicate-selectors": null,
+    "selector-type-no-unknown": [true, {
+      "ignoreTypes": ["$dummyValue"]
+    }]
+  }
+}