Split out debug to a sysext and tarball for debuginfod

This is to be used in combination with https://gitlab.com/freedesktop-sdk/infrastructure/freedesktop-sdk-docker-images/-/merge_requests/440

The container needs some volumes mounted in /var/lib/debug-images (A lot, like 100G if we keep 10 versions). A volume in /root, around 2% of it, so like 2G. And also probably /tmp, though it might not be needed.

HTTP on port 8002. Should get a reverse proxy in front and allow only requests starting with /buildid/.

Once we have an URL for it, we can add it into /etc/debuginfod/gnome-os.urls. For now it can be tested by setting DEBUGINFOD_URLS variable.

Here is the docker-compose.yaml I have used to test it:

---
version: '3'
services:
  debuginfod:
    image: registry.gitlab.com/freedesktop-sdk/infrastructure/freedesktop-sdk-docker-images/debuginfod:latest
    environment:
      HOME: /root
    ports:
      - "8002:8002"
    volumes:
      - data:/var/lib/debug-images
      - db:/root
      - tmp:/tmp
      - tmp:/var/tmp
volumes:
  data:
  db:
  tmp:

Then I used podman-compose exec debuginfod /update.sh to download the images.