Overhaul logging system

[rkingsbury]

Summary

The warning / logging system in pyEQL has been intentionally verbose and a bit haphazard, prompting confusion on the part of users (see #52 ). This PR overhauls the logging system by

1. Changing the loggers to conform more closely to python best practices
2. Adding a log_level kwarg to Solution.__init__ that allows users to control the level of verbosity of the messages they will see in stdout
3. Using logging levels (INFO/CRITICAL/ERROR/WARNING/DEBUG) rather than warnings in most cases

Closes #52

[codecov]

Codecov Report

Attention: Patch coverage is 70.23810% with 25 lines in your changes are missing coverage. Please review.

Project coverage is 82.08%. Comparing base (296be67) to head (9612d19).
Report is 9 commits behind head on main.

Files	Patch %	Lines
src/pyEQL/solution.py	62.50%	17 Missing and 1 partial ⚠️
src/pyEQL/engines.py	76.92%	3 Missing ⚠️
src/pyEQL/equilibrium.py	50.00%	3 Missing ⚠️
src/pyEQL/activity_correction.py	85.71%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #119      +/-   ##
==========================================
- Coverage   82.22%   82.08%   -0.15%     
==========================================
  Files          10        9       -1     
  Lines        1463     1457       -6     
  Branches      294      294              
==========================================
- Hits         1203     1196       -7     
  Misses        221      221              
- Partials       39       40       +1     

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