CHORE: SetupMaxwell refactoring to save fields and new SweepMaxwell for EC solvers

[gmalinve]

Description

**In this PR I want to:

• Improve the SetupMaxwell class in order to be able to save fields for all solvers.
• Add a new class in solve_sweep to handle EC freq. sweeps.
• Add/improve the already exisiting method to add frequency sweeps for EC in order to return the sweep object.**

Issue linked

Please mention the issue number or describe the problem this pull request addresses.

Checklist

• I have tested my changes locally.
• I have added necessary documentation or updated existing documentation.
• I have followed the coding style guidelines of this project.
• I have added appropriate tests (unit, integration, system).
• I have reviewed my changes before submitting this pull request.
• I have linked the issue or issues that are solved by the PR if any.
• I have agreed with the Contributor License Agreement (CLA).

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[codecov]

Codecov Report

Attention: Patch coverage is 90.00000% with 14 lines in your changes missing coverage. Please review.

Project coverage is 85.21%. Comparing base (2532517) to head (6c44dbe).
Report is 4 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5670      +/-   ##
==========================================
+ Coverage   83.73%   85.21%   +1.48%     
==========================================
  Files         156      156              
  Lines       61063    61171     +108     
==========================================
+ Hits        51131    52129     +998     
+ Misses       9932     9042     -890     

[jvela018]

@gmalinve ,

I made some general comments that I'd like to iterate over.

[maxcapodi78]

LGTM