Util/Monorepo: Deprecate Node 16 / Switch to native fetch() in Util

[holgerd77]

This is a follow-up more specific issue to #2837 , will close the old one.

We have got one single Node.js primitive usage left we want to get rid off, which is the usage of the https package for the fetch implementation in the Util provider.ts package.

For this we decided the following in one of the last calls: Node.js 18 introduces native fetch. We will therefore deprecate (in the sense of: remove) support for Node 16 on this occasion, which only has extended support for a very few months left anyhow, which will the free us to use native fetch in the Util provider module to replace the Node native stuff.

This should be done. 🙂

The PR should also make sure that CI/Actions is not run on Node 16 any more (then go to Node 18 I would say?), particularly in the Node versions tests Node 16 should be removed.

Update: just did a simple "16" search in the /.github folder, actually there are a lot of references to Node 16 which can either get updated or on several occasions I think would also just lead to a clean-up/deletion of code parts (if there are conditionals around Node 16 e.g.).