Null/NaN support in SiteWise

[hwandersman]

Is your feature request related to a problem? Please describe.
IoT SiteWise is preparing to release a new feature to allow null and NaN values. We need to test the backend datasource with the new SDK changes to fix things if this feature breaks the plugin.

There are 2 major changes:

1. NaN values will be supported in the doubleValue data type
2. A new data type called nullValue will be supported.

Describe the solution you'd like
We'd like to first check if these changes break anything on the data charts. If they do, then we want to simply ignore these values, or treat them as empty.

Describe alternatives you've considered
None

Additional context
We are planning to release this feature in the next few weeks and need to determine it's impact ASAP.

I have the GoLang build of the latest SDK with these model changes that we need to test. Can use some support for testing this locally.