Draft: Feature/software rapid backend

Note ❗ : During the research httpbin seems the best candidate...

A configurable backend which can be accessed directly or via any kind of CDN to get characteristics of the CDN.

Shall be used in automated testing of rapid-cdn.

Features:

• cachebility
• path configurability
• websocket included
• the code is in python distribution (kapibara, as it's a friendly guy or miodozer as that animal can survive anything)

Inspirations:

• https://github.com/georgyo/ifconfig.io
• https://lab.nexedi.com/nexedi/slapos/-/tree/3fdcac85a86a20f8bf1a1b82d34d382c3306409f/software/rapid-cdn/test
• https://httpbin.org/
• https://websockets.readthedocs.io/en/stable/