Initial ElectroNP flowsheet

[luohezhiming]

Fixes/Resolves:

(replace this with the issue # fixed or resolved, if no issue exists then a brief statement of what this PR does)

Summary/Motivation:

Initial implementation of electroNP flowsheet with anaerobic digester followed by electroNP unit.

Changes proposed in this PR:

• Add electroNP flowsheet
• Add tests
• Add scaling factor for electroNP_ZO
• Modify tests

Legal Acknowledgement

By contributing to this software project, I agree to the following terms and conditions for my contribution:

1. I agree my contributions are submitted under the license terms described in the LICENSE.txt file at the top level of this directory.
2. I represent I am authorized to make the contributions and grant the license. If my employer has rights to intellectual property that includes these contributions, I represent that I have received permission to make contributions and grant the required license on behalf of that employer.

[codecov]

Codecov Report

Attention: Patch coverage is 89.07104% with 20 lines in your changes missing coverage. Please review.

Project coverage is 95.56%. Comparing base (97c9adb) to head (063e52d).
Report is 296 commits behind head on main.

Files with missing lines	Patch %	Lines
...eets/case_studies/electroNP/electroNP_flowsheet.py	87.87%	20 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1032      +/-   ##
==========================================
- Coverage   95.60%   95.56%   -0.05%     
==========================================
  Files         307      308       +1     
  Lines       29334    29508     +174     
==========================================
+ Hits        28045    28199     +154     
- Misses       1289     1309      +20     

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[MarcusHolly]

With the exception of one small comment, this LGTM.

[adam-a-a]

Great job on this!