Improvement: Remove strong types from t8_3D_vec and t8_3D_point

[lenaploetzke]

Describe your changes here:
Closes #2130
Very open for suggestions

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[codecov]

Codecov Report

❌ Patch coverage is 51.28205% with 19 lines in your changes missing coverage. Please review.
✅ Project coverage is 77.89%. Comparing base (9f94c4e) to head (0e1c80b).

Files with missing lines	Patch %	Lines
src/t8_types/t8_vec.cxx	51.51%	16 Missing ⚠️
src/t8_types/t8_vec.hxx	40.00%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2139      +/-   ##
==========================================
- Coverage   77.95%   77.89%   -0.06%     
==========================================
  Files         113      112       -1     
  Lines       19089    19021      -68     
==========================================
- Hits        14881    14817      -64     
+ Misses       4208     4204       -4     

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[sandro-elsweijer]

This is a bit inconsistent. We have a using for vectors, but not for points and sometimes we have using and sometimes typedef.

[lenaploetzke]

The inconsistency between using and typedef is because i cannot use templates with typedefs. But i will change everything to using as this is preferred for modern cpp

[sandro-elsweijer]

This was only for the C interface, since we needed a non owning strong type. But now, we can just use a normal std::span and do not need a wrapper.

[lenaploetzke]

Ah, i got it now, thank you!

[sandro-elsweijer]

What you you think, do we still need the differentiation between vectors and points or is a general dimensional type sufficient?

[sandro-elsweijer]

We could keep the vector name, since a vector is not only a vector in a geometric sense, but also a one-dimensional tensor.

[lenaploetzke]

No i also think that one dimensional object is enough. And yes i agree that we can just name it t8_vec and not t8_dimensional. I just defined both because we have so many usages of t8_3D_point in t8code...

[sandro-elsweijer]

Suggested change

	template <typename T>
	concept T8ContainerdoubleType = requires (T t) {
	template <typename TType>
	concept T8ContainerDoubleType = requires (TType type) {

[lenaploetzke]

Renamed to T8ContainerType and deleted the other one