Feature: probe scan cleanup

[dragonmux]

Detailed description

While testing an unrelated change set, we realised that the BMDA identification banner that's displayed was showing a duff output for the probe selected. This PR addresses this by properly sorting out how that output is generated and cleaning up some loose ends in the BMD firmware product and version string handling to help identify when things are going wrong.

The result changes

❯ src/blackmagic -s 8BB20695 -tv 1
Black Magic Debug App v1.9.0-1056-g95e768be
 for Black Magic Probe, ST-Link v2 and v3, CMSIS-DAP, J-Link and FTDI (MPSSE)
Using 1d50:6018 8BB20695 Black Magic Probe (Black Magic Debug)

to displaying

❯ src/blackmagic -s 8BB20695 -tv 1
Black Magic Debug App v1.9.0-1062-gf35b2403
 for Black Magic Probe, ST-Link v2 and v3, CMSIS-DAP, J-Link and FTDI (MPSSE)
Using 1d50:6018 8BB20695 Black Magic Debug
 Black Magic Probe v1.9.0-1023-g717ace3f-dirty

Your checklist for this pull request

• I've read the Code of Conduct
• I've read the guidelines for contributing to this repository
• It builds for hardware native (make PROBE_HOST=native)
• It builds as BMDA (make PROBE_HOST=hosted)
• I've tested it to the best of my ability
• My commit messages provide a useful short description of what the commits do

Closing issues

[esden]

LGTM