Transition ping2 firmwares into the ping1d directory

We intended to do this a year ago, and seemingly didn't get around it.

Ping2 was[^1] a device name for a physical hardware revision of the Blue Robotics [Ping Sonar](https://bluerobotics.com/store/sonars/echosounders/ping-sonar-r2-rp/). Both revisions use the same electronics, and the `ping1d` message set, so it makes more sense for both to pull from the `ping1d` folder, and just be represented by a major version number update.

The original variant uses `Ping-V3.2*_*.hex`, so I propose the `Ping2-V1.*.hex` firmware options should be renamed as `Ping-V4.*.hex`, which can then be used as the filtering correspondence in the place of the [current folder-name check in Ping Viewer](https://github.com/bluerobotics/ping-viewer/blob/master/src/sensor/ping.cpp#L86). Alternatively the current file naming could be maintained just within the `ping1d` folder, since the 2 [does at least correspond to the internal device revision](https://github.com/bluerobotics/ping-viewer/issues/1079#issuecomment-2142456103) anyway.

[^1]: It was decided the 2 was confusing because the sensor is still a 1-dimensional echosounder, so the product name has returned to just "Ping Sonar", with the hardware changeover documented in the revision history on the product page.

Start by reviewing the ping1d directory, the Ping2-V1.*.hex and Ping-V3.2*_*.hex naming, and Ping Viewer’s src/sensor/ping.cpp#L86 folder-name check. Resolve which naming approach is intended before changing files. Done means both hardware revisions are represented under ping1d and Ping Viewer can identify the firmware correctly.

Written by the indexing model from the issue text.