Update plot_states defaults

[ccoffrin]

I think be default we want plot_states to show all states, the user can trim it down when they know that is what they want.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 91.22%. Comparing base (19854d1) to head (175e04b).
Report is 3 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #21      +/-   ##
==========================================
+ Coverage   90.27%   91.22%   +0.95%     
==========================================
  Files           2        4       +2     
  Lines         185      228      +43     
==========================================
+ Hits          167      208      +41     
- Misses         18       20       +2     

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[zmorrell]

Does it make more sense to default to using all states, or would it be better to change it to be both num_states = 0 and energy_levels = 1 since the more likely default use case for people would be plotting ground states? That could prevent over-saturation on the x-axis for models larger than 4 qubits while also not providing an annoying limitation that only views low probability high energy states.