FIX: Register test now saves written data

The register test never saved the values it wrote to the registers in the h5 file. Therefore, the result can never be crosschecked after the scan has finished.

With this MR, now all the written random data is saved to the h5 file. Also, a bug was fixed, where the address list was never fully saved in the run config table in the h5 file, since the column was limited to 260 characters.