Add built in testing

[linknum23]

Add scripts and supporting infrastructure to support a units ability to test its basic functionality. This supports production's need for more automated testing.

In the future many of these test and their configurations will be accessible via the touchscreen on the front of an AmpliPi. For now they will exist as scripts.

[codecov-commenter]

Codecov Report

Merging #167 (a2fc646) into master (5c97edc) will increase coverage by 0.66%.
The diff coverage is 72.50%.

@@            Coverage Diff             @@
##           master     #167      +/-   ##
==========================================
+ Coverage   56.53%   57.20%   +0.66%     
==========================================
  Files          11       11              
  Lines        2432     2484      +52     
==========================================
+ Hits         1375     1421      +46     
- Misses       1057     1063       +6     

Flag	Coverage Δ
unittests	57.20% <72.50%> (+0.66%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
amplipi/streams.py	46.66% <0.00%> (ø)
amplipi/hw.py	32.99% <5.55%> (-1.40%)	⬇️
amplipi/rt.py	24.07% <40.00%> (+0.24%)	⬆️
amplipi/ctrl.py	82.77% <97.29%> (+0.53%)	⬆️
amplipi/app.py	79.41% <100.00%> (+0.62%)	⬆️
amplipi/models.py	94.27% <100.00%> (+0.18%)	⬆️
amplipi/utils.py	69.84% <0.00%> (+4.76%)	⬆️

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