rootless implementation

[madelen-at-work]

Describe your changes

Brings in same changes as Docker ACAP PR 107
NOTE! Known issues

• Only uid and gid are properly mapped between device and containers, not the other groups that the user is a member of. This means that resources on the device, even if they are volume or device mounted can be inaccesible inisde the container. This can also affect usage of unsuported dbus methods from the container
• iptables use is disabled
• The docker.socket group ownership is set to addon - ideally we would want to change this to e.g. sdk
• Symlinking done in postinstallscript.sh needs to be handled diffrently when AllowRoot is removed

Other:

• Documentation will be handled in separate PR

Checklist before requesting a review

• I have performed a self-review of my own code
• I have verified that the code builds perfectly fine on my local system
• I have added tests that prove my fix is effective or that my feature works
• I have commented my code, particularly in hard-to-understand areas
• I have verified that my code follows the style already available in the repository
• I have made corresponding changes to the documentation