Add support for CAMS wildfire parameters

[tweska]

This PR adds support for mapping and encoding CAMS wildfire parameters.

📋 Metkit Documentation 📋
https://sites.ecmwf.int/docs/metkit/pull-requests/PR-249

[codecov-commenter]

Codecov Report

❌ Patch coverage is 17.33333% with 62 lines in your changes missing coverage. Please review.
✅ Project coverage is 50.79%. Comparing base (d680e1d) to head (af72565).
⚠️ Report is 14 commits behind head on develop.

Files with missing lines	Patch %	Lines
src/metkit/mars2mars/mappings/rules/chemical.h	19.35%	50 Missing ⚠️
...ackend/concepts/point-in-time/pointInTimeMatcher.h	0.00%	5 Missing ⚠️
...ib/backend/concepts/statistics/statisticsMatcher.h	20.00%	4 Missing ⚠️
.../backend/concepts/composition/compositionMatcher.h	0.00%	3 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #249      +/-   ##
===========================================
- Coverage    50.95%   50.79%   -0.17%     
===========================================
  Files          384      385       +1     
  Lines        15467    15548      +81     
  Branches      1310     1314       +4     
===========================================
+ Hits          7881     7897      +16     
- Misses        7586     7651      +65     

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[MircoValentiniECMWF]

Everything seems ok.