feat(tab): add format for prev active tab

[dj95]

This pull request adds support for theming the previous active tab to help with the ToggleTab functionality. It's related to discussion https://github.com/dj95/zjstatus/discussions/115

Unfortunately the tab history is only received via the SessionInfo event, which makes it currently not really satisfying to use the feature, as the highlight will lag behind the actual action. I'll leave this pull request open until we receive a way to get the updated tab history on tab change events.