Move old serialization code to the namespace old::data

[RiscadoA]

Separated this from the new serialization PR so that it doesn't get too cluttered.
This will be useful to tell which parts of the code need to be refactored later on.

[codecov]

Codecov Report

Patch coverage: 74.49% and project coverage change: +3.45 🎉

Comparison is base (d1169a0) 24.55% compared to head (bca3566) 28.01%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #437      +/-   ##
==========================================
+ Coverage   24.55%   28.01%   +3.45%     
==========================================
  Files          86      106      +20     
  Lines        7005     7461     +456     
==========================================
+ Hits         1720     2090     +370     
- Misses       5285     5371      +86     

Impacted Files	Coverage Δ
core/include/cubos/core/data/binary_serializer.hpp	100.00% <ø> (ø)
core/include/cubos/core/data/context.hpp	100.00% <ø> (ø)
core/include/cubos/core/data/debug_serializer.hpp	0.00% <ø> (ø)
core/include/cubos/core/data/deserializer.hpp	22.72% <ø> (ø)
core/include/cubos/core/data/package.hpp	80.00% <ø> (ø)
core/include/cubos/core/data/serialization_map.hpp	69.23% <ø> (ø)
core/include/cubos/core/data/serializer.hpp	25.00% <ø> (ø)
core/include/cubos/core/ecs/commands.hpp	95.65% <ø> (ø)
core/include/cubos/core/ecs/component_manager.hpp	100.00% <ø> (ø)
core/include/cubos/core/ecs/world.hpp	88.88% <ø> (ø)
... and 53 more

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