Use public interface for instrument in parameters

[jenshnielsen]

• Avoid setting instrument via private _instrument attribute but pass it to base class
• Use public property as getter
• Update example notebook to do the same

[codecov]

Codecov Report

Merging #3187 (198de9b) into master (4c1e64c) will increase coverage by 0.00%.
The diff coverage is 24.13%.

@@           Coverage Diff           @@
##           master    #3187   +/-   ##
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  Coverage   65.92%   65.92%           
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  Files         218      218           
  Lines       28910    28902    -8     
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- Hits        19058    19055    -3     
+ Misses       9852     9847    -5