Introduce eslint and prettier for features and start using it (#7306)

* Introduce package for sharing eslint and prettier configurations

Co-authored-by: Mikko Aspiala <mikko.aspiala@gmail.com>

Signed-off-by: Janne Savolainen <janne.savolainen@live.fi>

* Start using eslint and prettier in packages

Co-authored-by: Mikko Aspiala <mikko.aspiala@gmail.com>

Signed-off-by: Janne Savolainen <janne.savolainen@live.fi>

---------

Signed-off-by: Janne Savolainen <janne.savolainen@live.fi>

packages/infrastructure/eslint-config/README.md

@@ -0,0 +1,32 @@
+# Lens Code Style
+
+**Note:** This package contains Eslint and Prettier configurations, name of package is `@k8slens/eslint-config` just because Eslint has arbitrary requirement (https://eslint.org/docs/latest/extend/shareable-configs).
+
+## Usage
+
+1. Install `@k8slens/eslint-config`
+2. Create `.prettierrc` that contains `"@k8slens/eslint-config/prettier"`
+3. Add a `.eslintrc.js` that extends `@k8slens/eslint-config/eslint`, for example:
+
+```
+module.exports = {
+  extends: "@k8slens/eslint-config/eslint",
+  parserOptions: {
+    project: "./tsconfig.json"
+  }
+};
+```
+
+4. Add linting and formatting scripts to `package.json`
+
+```
+{
+  "scripts": {
+    "lint": "lens-lint",
+    "lint:fix": "lens-lint --fix"
+  }
+}
+```
+
+6. Run `npm run lint` to lint
+7. Run `npm run format` to fix all formatting