Add two nRF52 boards.
Add two nRF52 boards.

- RedBearLab-BLE-Nano2 (ID 1093).
- Seeed 96Boards Nitrogen (ID 9014).
- Change originally came from PR #344.

mesheven/pyOCD,pyocd/pyOCD,flit/pyOCD,mesheven/pyOCD,flit/pyOCD,mbedmicro/pyOCD,mbedmicro/pyOCD,mesheven/pyOCD,mbedmicro/pyOCD,pyocd/pyOCD