[Feat]: add support for systemd socket activation

[rgl]

Is your feature request related to a problem? Please describe.

I would like to configure zot to use a privileged port like 80 or 443 without granting it the CAP_NET_BIND_SERVICE capability.

Describe the solution you'd like

Would like to configure Zot to use systemd Socket Activation.

For more information, please see:

• https://0pointer.de/blog/projects/socket-activated-containers.html
• https://www.sobyte.net/post/2022-01/systemd-socket-activation/

Describe alternatives you've considered

No response

Additional context

No response

[rchincha]

@rgl thanks for filing this issue.
Do you want to give a shot at a PR?
https://github.com/project-zot/zot/blob/main/examples/zot.service

[rgl]

I can!

Just so we are on the same page, this means that I will modify the following code, OK?

https://github.com/project-zot/zot/blob/v2.0.0/pkg/api/controller.go#L145-L168

[rchincha]

@rgl would also just add another zot.socket-service file with [Socket] directive?

[rgl]

@rchincha the PR is at #2186.

please be aware that I've updated the go.mod too, which I'm unsure if should be included in the PR. please advice in the PR issue.