[Feat.] Multi-account containers implimentation

[LiamillionSS]

This request would be for allowing the separation of the cache, cookies, and sessions into isolated containers. Firefox's distinction over chromium is that it allows for this to be done per TAB rather than per window so multiple logins and accounts can be managed from a single browser window.

How firefox presents this to the user:

[webbeef]

There's already some support to have separate cookies & storage. See for instance https://github.com/servo/servo/blob/974e22773668cd95e78d19edd4190c04bb6616cb/components/net/resource_thread.rs#L181 that creates normal and private http states to support private sessions. I think we could extend that mechanism to support container tabs.

[arihant2math]

There is a zulip thread with a document about implementation:

Thread: https://servo.zulipchat.com/#narrow/channel/263398-general/topic/Storage.20.26.20Persistence/with/544725217 Document: https://docs.google.com/document/d/1NCWXNY2zjmRV8ExfNdstb2-5bc1MtfAGh8aC3mcSIfw/edit?usp=sharing

Due to other concerns the implementation of this is stalled, but this would provide containers support.

[arihant2math]

I'll add that the system it proposes can be done on a per-tab or per-window basis, it's really up to the embedder.