Modify the OpenAPI for missing one implementation to include the feature IDs

[jcscottiii]

Building on #1109, we want to expose that new data.

The openapi document should be modified to allow for that metadata for each data point.

We may want to stop using BrowserReleaseFeatureMetricsPage (and BrowserReleaseFeatureMetric) and instead create new types for the missing one implementation endpoint. But non breaking changes