RZ1017 when using where in a @typeparam constraint

[chsienki]

When adding a where clause to a @typeparam directive the IDE shows error RZ1017 but the code compiles correctly.

Repro steps:

1. Create a new Blazor Server App, target framework net6.0
2. Open Counter.razor
3. Add:

@typeparam T1
@typeparam T2 where T2 : T1

4. Observe the error
5. F5 compiles successfully

Interestingly changing the target framework to 8.0 seems to fix the issue, and remains fixed even after switching back to 6.0.

Also reported here: https://stackoverflow.com/questions/72095268/net6-blazor-typeparam-where-constraint-error-rz1017

[chsienki]

Closing as a dupe of #8572