Cannot generate `protected` method in `sealed` type with `managedOverride` set to `override`

[jpobst]

If you attempt to fix a protected method in a sealed type that is not getting automatically set to override by using 'managedOverride'='override', the method will emitted as private.

This is because we attempt to fixup protected void Foo () { ... } in a sealed type when it isn't an override because it is a warning in C#.

However, this fixup does not take managedOverride into account.

https://github.com/xamarin/java.interop/blob/main/tools/generator/Java.Interop.Tools.Generator.Transformation/SealedProtectedFixups.cs#L13-L14

We should see if the user has set managedOverride to override, and if so, do not change the method to private.