Raise DNN Dependency from 9.4 to 9.9

[WillStrohl]

Is your feature request related to a problem?

There is no problem, but we need to continue to raise the bar of the version of DNN Platform that we're building against. This is for many reasons, not the least of which is to simply receive the benefits of integrating with a newer version of DNN.

Describe the solution you'd like

Raise the dependent DNN Platform version from 9.4 to 9.9. It would be ideal to raise it to at least 9.10.02, but it's also far more realistic to not raise the dependency too far, too quickly. Otherwise, there might be various issues with upgrade adoption.

Raising this dependency will be easy, since it's managed by Nuget.

Describe alternatives you've considered

N/A

Additional context

It may be necessary to update any additional DNN API endpoint changes that might be discovered at compile time.

[WillStrohl]

Should we consider 9.8 instead of 9.9? 🤔

[WillStrohl]

Currently targeting 9.9, but there are a lot of missing references or something from previous commits. I have several missing properties and methods in the module right now.