Switch to dynamic_cast instead of string comparison for product retrieval

[knoepfel]

Dynamic casts were originally avoided when retrieving data products due to various RTTI difficulties across plugins. This PR restores them.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

❌ Your project check has failed because the head coverage (76.58%) is below the target coverage (80.00%). You can increase the head coverage or adjust the target coverage.

@@            Coverage Diff             @@
##             main     #203      +/-   ##
==========================================
- Coverage   76.61%   76.58%   -0.04%     
==========================================
  Files         124      124              
  Lines        2733     2733              
  Branches      475      475              
==========================================
- Hits         2094     2093       -1     
  Misses        446      446              
- Partials      193      194       +1     

Flag	Coverage Δ
unittests	76.58% <100.00%> (-0.04%)	⬇️

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Files with missing lines	Coverage Δ
phlex/model/products.hpp	95.00% <100.00%> (ø)

... and 5 files with indirect coverage changes

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