Changes to GAC model and GAC example flowsheet to solve when MaterialFlowBasis.mass

[hunterbarber]

Fixes/Resolves:

Changes to GAC model and GAC example flowsheet to solve when MaterialFlowBasis.mass

Summary/Motivation:

Improve GAC functionality with newer MCAS flow basis options

Changes proposed in this PR:

• Change core GAC model to handle when MCAS MaterialFlowBasis.mass
• Change test file to cover changes
• Add mass basis as an option to the UI and example files

Legal Acknowledgement

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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 92.30769% with 2 lines in your changes are missing coverage. Please review.

Project coverage is 94.38%. Comparing base (44468b7) to head (5b634e3).

Files	Patch %	Lines
watertap/examples/flowsheets/gac/gac_ui.py	75.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1295      +/-   ##
==========================================
- Coverage   94.39%   94.38%   -0.01%     
==========================================
  Files         371      371              
  Lines       37922    37941      +19     
==========================================
+ Hits        35795    35812      +17     
- Misses       2127     2129       +2     

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[MarcusHolly]

One small type in the UI - otherwise LGTM

[savannahsakhai]

LGTM