Add missing convention-required Platform variables to AZFP

[imranmaj]

• Adds missing convention-required Platform variables to AZFP
• Adds tests for those variables

Part of #649 and #592

[codecov-commenter]

Codecov Report

Merging #654 (d3b1a7a) into dev (fc253c1) will decrease coverage by 5.39%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##              dev     #654      +/-   ##
==========================================
- Coverage   78.75%   73.35%   -5.40%     
==========================================
  Files          42       15      -27     
  Lines        3784     2327    -1457     
==========================================
- Hits         2980     1707    -1273     
+ Misses        804      620     -184     

Flag	Coverage Δ
unittests	73.35% <100.00%> (-5.40%)	⬇️

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

Impacted Files	Coverage Δ
echopype/convert/set_groups_azfp.py	98.38% <100.00%> (ø)
echopype/convert/set_groups_base.py	88.17% <0.00%> (-2.16%)	⬇️
echopype/convert/utils/ek_raw_parsers.py	54.90% <0.00%> (-0.17%)	⬇️
echopype/calibrate/calibrate_base.py
echopype/qc/api.py
echopype/utils/coding.py
echopype/echodata/widgets/widgets.py
echopype/__init__.py
echopype/echodata/convention/__init__.py
echopype/calibrate/calibrate_ek.py
... and 20 more

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[leewujung]

LGTM! Thanks!