Add typing to afg3000 driver

[jenshnielsen]

This would have caught the incorrect validator usage from #115

Also rewrite the driver to use the log attached to the instrument already

[codecov-commenter]

Codecov Report

Merging #118 (9cd0388) into master (0519fe3) will increase coverage by 0.00%.
The diff coverage is 0.00%.

@@           Coverage Diff           @@
##           master     #118   +/-   ##
=======================================
  Coverage   19.85%   19.85%           
=======================================
  Files         121      121           
  Lines       14709    14708    -1     
=======================================
  Hits         2920     2920           
+ Misses      11789    11788    -1     

Impacted Files	Coverage Δ
...codes_contrib_drivers/drivers/Tektronix/AFG3000.py	0.00% <0.00%> (ø)

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