Feature request: Enhance the tab group api to support the new pinning functionality

[tconfrey]

Recently added Chromium functionality allows tab groups to be pinned to the bookmarks bar. This causes them to be persisted and potentially replicated across environments. The user experience of tab groups has thereby been significantly changed and enhanced, however there is no access or even visibility to the functionality from the chrome apis.

Minimal visibility could be added as follows:

• Add a tabGroup.pinned (true | false) property and support it in the tabGroups.updated event.
• Include closed pinned tab groups in the tabGroups.query response.

Complete support, which might imply additional permissions, would also require:

• A pin/unpin method on the tabGroups class.
• An open/close method on the tabGroups class.
• An ability to query and update the urls associated with a closed pinned tab group.
• Event support for the above.