Add the ability to assign proxies to containers

[notDavid]

As the title says... please consider implementing the ability to assign proxies to specific containers.

Thank you.

[hensm]

Sure, I'll look at adding it when I next have some time to work on this.

[notDavid]

Thank you, would be great!

Fyi perhaps this is useful...: https://github.com/bekh6ex/firefox-container-proxy