Add support for multi-window

[Brandon-T]

Problem Description

• Add support for Multi-Window on iPad

Feature Overview

• The browser should be able to have multiple windows side by side. For example, Safari allows it.
• You should have private and regular modes side by side if the user wishes.
• Should have a button to open multiple windows.
• Optionally should allow dragging a tab from one window to another.
• Optionally should allow merging one window with another.

[Uni-verse]

Verified on iPad (7th Gen) running iPadOS 16.5.1 using version 1.57 (23.8.28.18)

Settings Menu (Private Tabs)

• Ensured that Private Tabs menu is shown for normal and private tabs but not in PBM.

Example	Example

Actions / Context Menu

• Ensured that Open in New Private Window & Open in New Window appear in the context menu.
• Ensured that tab is opened in the appropriate window/mode when using the Open in New Private Window & Open in New Window.
• Ensured that new actions show up in context menu in private and normal tabs.

Example	Example	Example	Example	Example

Menus / Icons / Onboarding in Windowed Mode

• Ensured Playlist, Brave Wallet, and Reader Mode icons are displayed in windowed mode.
• Ensured User is able to interact with icons in windowed mode.
• Ensured that onboarding pop-ups are shown while in split view.

Example	Example	Example	Example

Encountered:
#7976
#7978

Screen Modes

• Ensured that user is able to the different Screen Modes while having multiple windows open.

Example	Example

Windows View

• Ensured user is able to view all instances of brave when opening app or when using Show All Windows from the home screen context menu
• Ensured closing windows by swiping

Example	Example	Example	Example

Existing Profile

• Ensured opening private tabs and private tab windows works on existing profile.
• Ensured entering split view modes works.
• Ensured opening new window for normal tabs works from the context menus.