ble,serial: rework adaptor and drivers

[gen2thomas]

Solved issues and/or description of the change

This PR rework the BLE adaptor and Sphero drivers by splitting off in this parts:

• serial port adaptor (UART Support #371 and maybe a start point for HX711 Support #1050)
• BLE client adaptor
• drivers for serial port, introduced with the "Sphero"
• drivers for BLE, introduced with all BLE based drivers in the former ble adaptor package

This is one step in direction to open the possibility to add more BLE drivers, see #1004 .
The existing gpio-migration guide was moved to driver level and improved for the changes.

Manual test

none

Checklist

• The PR's target branch is 'hybridgroup:dev'
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes (e.g. by run make test_race)
• No linter errors exist locally (e.g. by run make fmt_check)
• I have performed a self-review of my own code

If this is a new driver or adaptor:

• I have added the name to the corresponding README.md
• I have added an example to see how to setup and use it
• I have checked or build at least my new example (e.g. by run make examples_check)