Cannot write to backup directory - "/"

[donhardman]

When we restore a backup to the root directory, for example, using --backup-dir=/, and there's a file in the state directory, we can't restore it because of an error.

[donhardman]

Following an investigation, it was determined that the issue does not lie with the backup itself but rather with how we are preserving the path. Initially, I mistakenly assumed that we could include a .gitkeep file inside the state directory because we map it to the root directory. To address this, I implemented a workaround in the Demo project.

Additionally, during the investigation, I discovered files within the tmp directory that should not be included in the Docker image. Consequently, I created a pull request to address this issue: manticoresoftware/docker#73