* fix(typescript): add missing extension to imports in typescript
This is required for the types to work with the new
`--module-resolution=node16`.
The list of places to fix was obtained by a crude script:
```sh
rg -g'**/*.ts' -g'!**/*.test.ts' ' from\s+.\.' | rg -v '\.js'
```
References #1765
* add missing extensions
* revert tsconfig
* prettier
* fix test files for NodeNext
* prettier
* changelog entry
* prettier
* prettier
* prettier
---------
Co-authored-by: Andrey Lushnikov <aslushnikov@gmail.com>
* Fix acessability issue
* Additionally adapted the test
* Added more accessability tests
* Updated the testing documentation
to take the fact that accessability checks cover only
rendered content into account
---------
Co-authored-by: Dominikus Hellgartner <dominikus.hellgartner@gmail.com>