chore: further simplify parsing from YAML

[RomainMuller]

Directly deserialize into the end data structure and get rid of all the older APIs that were used to that purpose. Added test coverage around conditions, etc...

Moved from HashMap to IndexMap to preserve order of elements where relevant, as this provides a deterministic, reliable experience to customers.

[codecov]

Codecov Report

Patch coverage: 78.53% and project coverage change: +10.00 🎉

Comparison is base (97fa628) 47.48% compared to head (ac8998a) 57.48%.

Additional details and impacted files

@@             Coverage Diff             @@
##             main     #121       +/-   ##
===========================================
+ Coverage   47.48%   57.48%   +10.00%     
===========================================
  Files          21       21               
  Lines        2622     2585       -37     
===========================================
+ Hits         1245     1486      +241     
+ Misses       1377     1099      -278     

Impacted Files	Coverage Δ
src/errors/mod.rs	41.66% <0.00%> (-13.89%)	⬇️
src/ir/constructor.rs	0.00% <0.00%> (ø)
src/ir/importer.rs	0.00% <0.00%> (ø)
src/ir/outputs.rs	0.00% <0.00%> (ø)
src/parser/output.rs	0.00% <0.00%> (-8.07%)	⬇️
src/parser/parameters.rs	0.00% <0.00%> (-12.50%)	⬇️
src/synthesizer/typescript_synthesizer.rs	6.97% <0.00%> (ø)
src/ir/resources.rs	21.87% <14.89%> (+1.10%)	⬆️
src/specification/mod.rs	41.52% <25.00%> (ø)
src/ir/mappings.rs	87.32% <33.33%> (+1.21%)	⬆️
... and 7 more

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