[DT-1077] typescriptify datasetstatistics and fix

[s-rubenstein]

Addresses

I noticed the issue appeared to be based on properties missing, so I added a test with no additional properties that still renders.

I opted not to put in the additional effort to typescriptify the test, because test files are much less impact as js vs ts, and if we decide to move unit tests to jest eventually, I wanted to prioritize effort.

Summary

---

Have you read Terra's Contributing Guide lately? If not, do that first.

• Label PR with a Jira ticket number and include a link to the ticket
• Label PR with a security risk modifier [no, low, medium, high]
• PR describes scope of changes
• Get a minimum of one thumbs worth of review, preferably two if enough team members are available
• Get PO sign-off for all non-trivial UI or workflow changes
• Verify all tests go green
• Test this change deployed correctly and works on dev environment after deployment

[s-rubenstein]

This file is side by side with a models.js file, and the capitalization being the only difference was causing issues. Given this was only used in one place I just moved it.