Refactor CodesContent with new CodesHandle

[pgeier]

Description

This PR creates a copy of CodesContent with the name CodesDataContent.
CodesDataContent is using the new CodesHandle API wrapper to avoid using eccodes directly.

• The MallocCodesContent has been removed as it had wrong behaviour - after a modification to the handle in returned the old data array.
• codesHandleFromFile has been extended with an optional offset parameter
• new call codesHandleFromStream
• Additional exception CodesWrongLength

Depending downstream dependencies are fdb - a separate PR (ecmwf/fdb#198) - unfortunately we can not test the CI using both.

Contributor Declaration

By opening this pull request, I affirm the following:

• All authors agree to the Contributor License Agreement.
• The code follows the project's coding standards.
• I have performed self-review and added comments where needed.
• I have added or updated tests to verify that my changes are effective and functional.
• I have run all existing tests and confirmed they pass.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 52.29358% with 52 lines in your changes missing coverage. Please review.
✅ Project coverage is 54.18%. Comparing base (15a0584) to head (85684a2).

Files with missing lines	Patch %	Lines
src/metkit/codes/CodesDataContent.cc	25.00%	42 Missing ⚠️
src/metkit/codes/api/CodesAPI.cc	76.66%	7 Missing ⚠️
src/metkit/codes/BufrContent.cc	33.33%	2 Missing ⚠️
src/metkit/codes/BUFRDecoder.cc	0.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #128      +/-   ##
===========================================
- Coverage    54.31%   54.18%   -0.14%     
===========================================
  Files          298      300       +2     
  Lines        11514    11564      +50     
  Branches      1021     1025       +4     
===========================================
+ Hits          6254     6266      +12     
- Misses        5260     5298      +38     

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[Ozaq]

We need to run this past @simondsmart because we might impact performance due to the additional copy.

[simondsmart]

This looks great.