Enable clients with capability to set the encryption key of a resource data group

[feliperoos]

Hi @martinweismann

This hopes to close Issue #273 by enabling clients to specify an array with the content encryption key when creating a resource data group. This is still a WIP, I'd like to get your feedbacks on it first. If you think this is a good move, I'll improve testing.

[codecov]

Codecov Report

Merging #274 (32f1339) into develop (431d803) will decrease coverage by 0.00%.
The diff coverage is 66.66%.

@@             Coverage Diff             @@
##           develop     #274      +/-   ##
===========================================
- Coverage    72.84%   72.83%   -0.01%     
===========================================
  Files          418      418              
  Lines        23274    23280       +6     
===========================================
+ Hits         16954    16957       +3     
- Misses        6320     6323       +3     

Impacted Files	Coverage Δ
Include/API/lib3mf_keystore.hpp	100.00% <ø> (ø)
Source/API/lib3mf_keystore.cpp	82.97% <66.66%> (-1.47%)	⬇️
Autogenerated/Source/lib3mf_interfacewrapper.cpp	65.80% <0.00%> (-0.01%)	⬇️
Autogenerated/Source/lib3mf_interfaces.hpp	100.00% <0.00%> (ø)
Autogenerated/Bindings/Cpp/lib3mf_implicit.hpp	94.99% <0.00%> (ø)

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