Add stylelint and scss configs

- see https://github.com/stylelint/stylelint/blob/main/docs/user-guide/get-started.md#using-a-community-shared-config

- note that adding postcss@8 is necessary for the scss config to work - see stylelint-scss/stylelint-config-standard-scss#5

package.json

@@ -210,6 +210,7 @@
     "nodegit": "^0.28.0-alpha.10",
     "path": "^0.12.7",
     "pegjs": "^0.10.0",
+    "postcss": "^8.4.19",
     "postcss-cli": "^7.1.2",
     "postcss-inline-svg": "^4.1.0",
     "postcss-loader": "^7.0.1",
@@ -241,6 +242,9 @@
     "shelljs": "^0.8.4",
     "start-server-and-test": "^1.11.3",
     "style-loader": "^3.3.1",
+    "stylelint": "^14.15.0",
+    "stylelint-config-prettier-scss": "^0.0.1",
+    "stylelint-config-standard-scss": "^6.1.0",
     "terser-webpack-plugin": "^5.3.5",
     "typescript": "4.5.3",
     "uglifyjs-webpack-plugin": "^2.2.0",