Ability to use a split tunnelling on MAC for specific containers

[data-sync-user]

Feature Description: Users would like to have the ability to use a multi-account container without this being routed through the VPN when the VPN is turned on.

Meaning they would like to have the ability to bypass certain containers from the VPN when this is on.

User#1: -Streaming services would not be blocked due to VPN being active. User#2: Being able to split-tunnel a container directly to my IPS (no VPN) would enable using a single browser (Firefox) with all websites, including those that block the VPN (mainly streaming services like Netflix, HBO, etc) without having to turn the VPN on/off.

Yet another great feature would be if certain privacy settings could be used for certain containers, or if certain websites could be whitelisted from certain privacy features. I'm mainly thinking about network.http.sendRefererHeader, network.http.referer.XOriginPolicy and resistfingerprinting (I know there is a whitelist for RFP but it's not working on e.g. icloud,com login) which all have a tendency to break websites (I haven't really had any breakage problems with FPI, oddly enough).

**What was the last version you used where you thought this idea would be useful? ** Mozilla 2.8.3

How does this improve your experience? Users would like to have the ability set a multi-account container without the VPN when the VPN is turned on.

Additionally this could be a way to mitigate blocked websites that detect VPN usage.

┆Issue is synchronized with this Jira Task ┆author: Joseph Anthony Cuevas