Refactor ABM code: Rename EPI to MIO and migration to mobility and World to Model

[xsaschako]

Changes and Information

Please briefly list the changes made, additional Information and what the Reviewer should look out for:

• changed "EPI" to "MIO"
• changed all appearances of "migration" or similar to "mobility" or similar
• renamed "ABM::World" to "ABM::Model"

Merge Request - Guideline Checklist

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Checks by code author

• Every addressed issue is linked (use the "Closes #ISSUE" keyword below)
• New code adheres to coding guidelines
• No large data files have been added (files should in sum not exceed 100 KB, avoid PDFs, Word docs, etc.)
• Tests are added for new functionality and a local test run was successful
• Appropriate documentation for new functionality has been added (Doxygen in the code and Markdown files if necessary)
• Proper attention to licenses, especially no new third-party software with conflicting license has been added
• (For ABM development) Checked benchmark results

Checks by code reviewer(s)

• Corresponding issue(s) is/are linked and addressed
• Code is clean of development artifacts (no deactivated or commented code lines, no debugging printouts, etc.)
• Appropriate unit tests have been added, CI passes and code coverage is acceptable (did not decrease)
• No large data files added in the whole history of commits(files should in sum not exceed 100 KB, avoid PDFs, Word docs, etc.)

[codecov]

Codecov Report

Attention: Patch coverage is 92.27273% with 17 lines in your changes missing coverage. Please review.

Project coverage is 96.12%. Comparing base (a97183a) to head (cb5b3ea).
Report is 1 commits behind head on main.

Files	Patch %	Lines
cpp/models/abm/model.cpp	76.59%	11 Missing ⚠️
...memilio/mobility/metapopulation_mobility_instant.h	95.91%	2 Missing ⚠️
...ilio/mobility/metapopulation_mobility_stochastic.h	86.66%	2 Missing ⚠️
cpp/models/abm/model.h	85.71%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #879      +/-   ##
==========================================
- Coverage   96.14%   96.12%   -0.02%     
==========================================
  Files         131      131              
  Lines       11047    11049       +2     
==========================================
  Hits        10621    10621              
- Misses        426      428       +2     

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[mknaranja]

I did a superficial review but would think that it looks very good. Thank you very much for the immense work.