Sidebar Improvements/Changes

Hi, I wanted to suggest a revamp to the sidebar and splitscreen capabilities of brave.
A lot of this is based off edge, but I would hope it could work better in brave with the builtin AdBlock. The ability to split tabs would be interesting, and also the ability to have sidebar support apps that open in their own instance would be helpful. this was discussed in multiple threads related to opera, and its one place brave is lacking compared to both edge and opera. Sidebars with apps are incredibly useful.