onewire(ds18b20): introduce 1-wire device access by sysfs and temp driver

[gen2thomas]

Solved issues and/or description of the change

Introduce the basic infrastructure for 1-wire devices. Basic means:

• no access to the bus master, so no manual add/remove of devices possible - automatic scan is mandatory
• no accesser switch implemented, so currently only sysfs is supported

Add a driver for DS18B20 as first example.

Manual test

• OS and Version (Win/Mac/Linux): Linux
• Adaptor(s) and/or driver(s): tinkerboard, raspi, DS18B20

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)