Tab and TabList Migration

Migration from v8

1. Replace occurrences of <Pivot> with <TabList>
2. Replace occurrences of <PivotItem> with <Tab>
3. Replace <PivotItem> content with handling onTabSelected to show/hide associated content.
4. Move PivotItem.headerText to be the content of Tab
5. Subscribe to onTabSelected to show/hide content when a tab is selected.

Migration from v0

1. Replace use of <Menu> with <TabList>
2. Replace items data with Tab instances, writing a map function as needed.