gpio: fix data race in StepperDriver

[gen2thomas]

Solved issues and/or description of the change

data race in StepperDriver and EasyDriver found by go test -race - fixed by rework of drivers and its tests

this partially fix #1017

additionally:

• huge rework (also again for EasyDriver, see pervious commit gpio: fix data race in EasyDriver #1025 ), test improvements and example adjustment
• add Sleep() function to prevent overheating
• add signal handler for os interrupts

Manual test

• OS and Version (Win/Mac/Linux): Linux
• Adaptor(s) and/or driver(s): raspi with stepper example and L298N based driver

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)
• No linter errors exist locally (e.g. by run make fmt_check)
• I have performed a self-review of my own code