Fix multi-dimensional world_axis_object_components/classes with CoordinateFrame

[Cadair]

I discovered this while working on some NDCube stuff for making a WCS with 3 distance (km) axes. We need this for the NDCube 2 release. 😄

Fixes #358

[codecov]

Codecov Report

Merging #356 (0ff3814) into master (b34be78) will increase coverage by 0.15%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #356      +/-   ##
==========================================
+ Coverage   90.23%   90.38%   +0.15%     
==========================================
  Files          32       32              
  Lines        5006     5066      +60     
==========================================
+ Hits         4517     4579      +62     
+ Misses        489      487       -2     

Impacted Files	Coverage Δ
gwcs/coordinate_frames.py	95.12% <100.00%> (+0.87%)	⬆️
gwcs/tests/conftest.py	88.31% <100.00%> (+0.39%)	⬆️
gwcs/tests/test_api.py	98.01% <100.00%> (+0.17%)	⬆️

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[nden]

LGTM.
@Cadair Can you rebase?

[Cadair]

@nden can you hold off merging this for a bit, I want to poke at #358 to see what the overlap is.

[Cadair]

ok @nden I have now updated this to also fix #358 I did it in one go to minimise the sillyness of appending integers to the names of the objects.

If you can see a better way of doing the deduplication please let me know, my brain isn't exactly on peak form this week.