Help wanted: code linting errors (Swift/Typescript)

[pbowyer]

I've added code linting to make it like other capacitor-community projects.

Unfortunately there are many linting errors, and I need your help to fix them.

How to help

1. Clone this repository
2. Checkout branch code-formatting
3. Run npm run lint to run all linters
4. Fix what it reports 😄
5. Run npm run lint again to check they're fixed
6. Submit a new pull request with your changes 🥳