extract and create meshtags

[jhdark]

Proposed changes

Allow for extraction and creation of meshtags from an OpenFOAM file

Types of changes

What types of changes does your code introduce to foam2dolfinx?

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Code refactoring
• Documentation Update (if none of the other choices apply)
• New tests

Checklist

• Unit tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)

Further comments

If this is a relatively large or complex change, kick off the discussion by explaining why you chose the solution you did and what alternatives you considered, etc...

[codecov]

Codecov Report

❌ Patch coverage is 98.85057% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 98.50%. Comparing base (d131553) to head (6d228ee).
⚠️ Report is 16 commits behind head on main.

Files with missing lines	Patch %	Lines
src/foam2dolfinx/open_foam_reader.py	98.77%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #35      +/-   ##
==========================================
+ Coverage   98.30%   98.50%   +0.20%     
==========================================
  Files           2        3       +1     
  Lines         118      268     +150     
==========================================
+ Hits          116      264     +148     
- Misses          2        4       +2     

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