Control Styles should be named

While investigating this, I noticed an issue for this that is a complete show stopper: there is no way to override the default TabViewItem style. Unlike some other controls, the TabViewItem does not follow the pattern of:

<Style TargetType="ControlName" BasedOn="DefaultControlNameStyle"/>

<Style x:Key="DefaultControlNameStyle" TargetType="ControlName">
...
</Style>

but rather just exposes the complete template as the default style leaving users with no choice of easily overriding the default style. However that is something that we would need for this feature to be easily usable. @ranjeshj @stmoy @StephenLPeters Is that something we can change to make that customization easier?

@michael-hawker FYI

Originally posted by @chingucoding in https://github.com/microsoft/microsoft-ui-xaml/issues/2587#issuecomment-732463534