Move tools/adafruit-nrfutil to tools package

**Is your feature request related to a problem? Please describe.**
current pre-built binary of adafruit-nrfutil for macos and win is rather heavy, we should make use of the Arduino tool package (like gcc, nrfjprog etc..) instead of including it in the BSP.

**Describe the solution you'd like**
update tool dependency https://github.com/adafruit/arduino-board-index/blob/gh-pages/bpt.ini#L293

Start with the linked bpt.ini entry around line 293 in the adafruit/arduino-board-index repository and compare how other tools such as gcc and nrfjprog are declared. Done means the adafruit-nrfutil dependency is updated there so it is provided through the Arduino tool package rather than bundled in the BSP.

Written by the indexing model from the issue text.