(Undone) Fix nodeList method in Node and add global node count tracking

[slacrherbst]

Fixes the Node method nodeList which was broken.

Also adds a class counter for Node to determine how many nodes exist in the system as a scaling metric.

[codecov-commenter]

Codecov Report

Attention: 2 lines in your changes are missing coverage. Please review.

Comparison is base (64ac9ce) 30.02% compared to head (e88b7e4) 30.06%.

Files	Patch %	Lines
python/pyrogue/_Node.py	66.66%	2 Missing ⚠️

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Additional details and impacted files

@@            Coverage Diff             @@
##             main     #982      +/-   ##
==========================================
+ Coverage   30.02%   30.06%   +0.03%     
==========================================
  Files          65       65              
  Lines        6634     6639       +5     
  Branches     1013     1013              
==========================================
+ Hits         1992     1996       +4     
- Misses       4485     4486       +1     
  Partials      157      157              

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[bengineerd]

This was mistakenly pushed to main instead of pre-release, then undone with a force push.
New PR is #983