First experimental branch: https://github.com/htmlhint/HTMLHint/tree/chore/typescript-sub-1

I created an initial process workflow to leave our current rollup build unchanged

@thedaviddias I think I want to request a first review!

There are still errors and warnings, but from now on it might be that we need to change code!
So we may push this into a beta branch?

eslint is currently configured to allow warnings so the build can be triggered
The tests are green and I didn't touched the tests!

For now I disabled some eslint rules and added some TODOs to resolve them later

This PR didn't touched runtime-code
This will be made in a next PR so we can track the changes in a better and more readable way

I have improved linting for the project so test folder is also linted with typescript checking and I improved linting with type-checking enabled.