hyper-examples: Update examples for `hyper`.

As a follow-up from this comment #1914 (comment 3188157) I decided to make a MR revisiting the examples for hyper.

Edit: Initially this MR also introduced a new example to create a custom ArtiHttpConnector. In agreement with @Diziet we decided to make a separate arti-hyper library for that. This MR now only contains updates for the currently already existing hyper examples.

Old MR description

This MR contains:
✅ Add example to create a custom ArtiHttpConnector to use with hyper (biggest chance) - nield/arti@e54f2457
✅ Remove unsafe request in example hyper-http-client-example - nield/arti@95478ee6
✅ Structure hyper example folder to use binaries instead of separate project for each example - nield/arti@95478ee6
✅ Add README.md - nield/arti@c7709e9b

This MR is still WIP because:
❌ The two already existing tests don't seem to work for me, I'll see if I can fix this.
❌ Bad weather in the CI pipeline so can't run checks.

Open for feedback.