Add More typing and fix linter

[DrRataplan]

Some assorted changes that should make contributing a bit easier:

• I improved typing for most often-used functions, like the XPaths ones, context-related etcetera with js-doc. This improves autocomplete a lot.
• I also refactored the mixin ForeElementMixin to just use inheritance from HTMLElement. This makes it easier to type. I'm now getting autocompletes with the visual-studio code language server (through emacs) on the this.* fields of Fore components that inherit from ForeElement.
• The linter is upgraded to eslint 9, the newest. This required moving the config to its own file (eslint.config.mjs) and some adapting of the open-wc eslint-config.
• Merge eslint and prettier together by using the correct plugins

[JoernT]

seems cypress tests are not liking it