driver/sigrok: Add sigrok driver for DMMs

[SmithChart]

Description
The SigrokDmmDriver wraps around a single channel DMM controlled by sigrok. It has been tested with Unit-T UT61C and UT61B devices but probably also works with other single chnnel DMMs.

This driver binds to a SigrokUsbDevice.
Make sure to select the correct driver for your DMM there.

Example usage:

resources:
  - SigrokUSBDevice:
      driver: uni-t-ut61c
      match:
        'ID_PATH': pci-0000:07:00.4-usb-0:2:1.0
drivers:
  - SigrokUt61DmmDriver: {}

Args:
bindings (dict): driver to use with sigrok

I'm already using this driver to read values from two DMMs in parallel during hardware testing:

volt_dmm = target.get_driver("SigrokDmmDriver", name="volt_dmm")
curr_dmm = target.get_driver("SigrokDmmDriver", name="curr_dmm")
volt_dmm.start(5)
curr_dmm.start(5)
dmm_volt = dmm_voltage_measure(self.volt_dmm.get_samples())
dmm_curr = dmm_current_measure(self.curr_dmm.get_samples())

Where the helper dmm_*_measure() makes sure the correct physical unit has been returned by the DMM, does averaging, etc.

Checklist

• Documentation for the feature
• Tests for the feature

• The arguments and description in doc/configuration.rst have been updated

• Add a section on how to use the feature to doc/usage.rst

• Add a section on how to use the feature to doc/development.rst

• PR has been tested

• Man pages have been regenerated

[codecov]

Codecov Report

Patch coverage: 31.1% and project coverage change: -0.3 ⚠️

Comparison is base (3dc17a9) 63.0% compared to head (94ffdda) 62.8%.

❗ Current head 94ffdda differs from pull request most recent head e921a4a. Consider uploading reports for the commit e921a4a to get more accurate results

Additional details and impacted files

@@           Coverage Diff            @@
##           master   #1141     +/-   ##
========================================
- Coverage    63.0%   62.8%   -0.3%     
========================================
  Files         159     159             
  Lines       11668   11795    +127     
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+ Hits         7362    7410     +48     
- Misses       4306    4385     +79     

Impacted Files	Coverage Δ
labgrid/driver/sigrokdriver.py	35.8% <29.5%> (-1.4%)	⬇️
labgrid/driver/__init__.py	100.0% <100.0%> (ø)

... and 14 files with indirect coverage changes

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[SmithChart]

@Bastian-Krause: I've updated my PR, please have another look. (Also fixed some typos here and there while I was on it...)

[Bastian-Krause]

Mh, SigrokCommon logs everything as SigrokDriver. That's confusing. We should fix that, not necessarily in this PR, though..

[SmithChart]

Seems like the best way would be to have a __attrs_post_init__() in each driver that sets up logging with the correct name.

[Bastian-Krause]

See #1293.

[SmithChart]

@Bastian-Krause: I've updated my PR, please have another look.

[Bastian-Krause]

Thanks!