Implement $searchMeta pipeline stage #2824
Description
Feature Request
| Q | A |
|---|---|
| New Feature | yes |
| RFC | no |
| BC Break | no |
Summary
Follow-up to #2460. While the $search stage has been implemented, $searchMeta has not as it's not entirely obvious how often this will be used. When it is implemented, it should not be added to the Stage class but only to Builder as it can only be used as the first stage in a pipeline.