Container Tab Groups Synchronisation per Serafim Dietrich

Isolated tab groups! Automatically syncs firefox native tab groups with contextual identities (Firefox Multi Account Containers):
- Creates a contextual identity (container) for each tab group, using the group’s name and color.
- Moves tabs into their corresponding containers when a tab group is created or updated.
- Cleans up containers when tab groups are removed, including moving tabs back to the default container.
- Supports multiple open windows.