Problem: Docker with Namespace-Remapping

As wished in https://github.com/fkie-cad/FACT_docker/issues/22 here is the issue to track the mentioned Problem down.

I am using Docker namespace remapping. I was able to solve the issues within the containers that are in the docker-compose.yml by adding " userns_mode: "host" " for each container as far as I could observe so far.

However, start.py loads the fact extraction container, but this fails because it seems to start without the "userns_mode: "host" " parameter. See also https://github.com/fkie-cad/FACT_core/issues/794. This looks very much like the same problem.
```
./start.py pull

[2022-07-29 13:33:41][install][INFO]: FACT Installer 1.2
[2022-07-29 13:33:41][install][INFO]: Your distribution (alpine 3.15.5) is not supported. FACT Installer requires Ubuntu 18.04, 20.04 or compatible!
[2022-07-29 13:33:41][backend][INFO]: Pulling fact extraction container
Traceback (most recent call last):
File "/opt/FACT_core/src/install.py", line 187, in .
install()
File "/opt/FACT_core/src/install.py", line 156, in install
install_docker_images(args)
File "/opt/FACT_core/src/install.py", line 180, in install_docker_images
backend_install_docker_images()
File "/opt/FACT_core/src/install/backend.py", line 80, in _install_docker_images
raise InstallationError(f'Failed to pull extraction container:\n{docker_process.stdout}')
helperFunctions.install.InstallationError: Failed to pull extraction container:
Using default tag: latest
Got permission denied while trying to connect to the Docker daemon socket at unix:///var/run/docker.sock: Post "http://%2Fvar%2Frun%2Fdocker.sock/v1.24/images/create?fromImage=fkiecad%2Ffact_extractor&tag=latest": dial unix /var/run/docker.sock: connect: permission denied
```

Maybe modifying the file metioned in https://github.com/fkie-cad/FACT_core/issues/794 could help?!

I will need to setup Namespace-Remapping on my non-dockerized FACT, than i could try and hopefully get any new information.
I'll report back as soon as i can.

Thanks again!

Start by reproducing ./start.py pull with Docker namespace remapping and read start.py, docker-compose.yml, src/install.py, and src/install/backend.py. Compare the extraction-container path with the containers defined in docker-compose.yml, using FACT_core issue 794 for context. Done means the extraction container can be pulled and started successfully under the reported setup.

Written by the indexing model from the issue text.