TS config improvals

[patric-eberle]

Pull request

This PR checks and extends the TS config file according to the recommendations from this video: https://www.youtube.com/watch?v=eJXVEju3XLM

I decided not to use noUncheckedIndexAccess thought, because it seems to conflict with some of our code (e.g. in Vue templates). But tried to remove shown issues where ever possible.

Ticket

331

Browser testing

• Please run all test scripts and also check the output in the browser (demo & storybook).

Checklist

• [x] I merged the current development branch (before testing)
• [x] Added JSDoc and styleguide demo
• [x] Tested all links in project relevant browsers
• [x] Tested all links in different screen sizes
• [x] Did run automated tests and linters
• [x] Did assign ticket
• [x] Double checked target branch

Review/Test checklist

• [ ] Did review code and documentation
• [ ] Tested all links in project relevant browsers
• [ ] Tested all links in different screen sizes
• [ ] Did check accessibility (Wave, only errors)
• [ ] Re-assign ticket to developer

[mob8607]

There is an existing PR https://github.com/valantic/vue-template/pull/332/files for this topic. Please check the differences and merge them together.

[patric-eberle]

@mob8607 I compared the two branches and merged the changes from the first one if missing or better solution. I also applied the requested changes from the first branch. Please check again.

[patric-eberle]

@BeneRichi can you please do an additional review of this PR. Mathias is blocked by projects.