Warn at codegen time about conflicting names in xmlns #29707
Description
Description
When there's a conflicting names in a XAML xmlns, the inflators used to pick the First() (but with ordering undefined). #29579 makes the inflation fail, at runtime or XamlC time.
We should be proactive and report a diagnostic warning at the time the code behind for the xaml (xmalg) is generated, so the issue can be reported in the IDE
Public API Changes
none
Intended Use-Case
/