Bugzilla

### Beta/Release Uplift Approval Request
* **User impact if declined**: Data Science will be lacking Telemetry they requested to monitor the success of the new search mode feature.
* **Is this code covered by automated tests?**: Yes
* **Has the fix been verified in Nightly?**: No
* **Needs manual test from QE?**: Yes
* **If yes, steps to reproduce**: 1. Open the address bar and select the Google one-off search button.
2. Observe that we enter Google search mode (a blue "Google" indicator is shown in the address bar). Click on the first result.
3. Open about:telemetry and search for `urlbar.picked.searchmode.oneoff`.
4. Observe that the key `0` has a value of `1`.
* **List of other uplifts needed**: None
* **Risk to taking this patch**: Low
* **Why is the change risky/not risky? (and alternatives if risky)**: This patch just records new telemetry from one place where we already record telemetry. The vast majority of the code is just Telemetry definitions, tests, and documentation.

I requested QE verification, but the worst case with this patch is that no/bogus data is recorded in a _new_ Telemetry probe I'm adding (so we'd just ignore it), so this could be uplifted before it's verified.
* **String changes made/needed**:

EDIT: Accidental post, please disregard.