refactor get_spice to build from source

[AndrewAnnex]

this is a big refactor of get_spice.py to allow spiceypy to build spice from source, apply patches from the NAIF, enabling ARM builds. Changes the names of some things so likely a bit broken.

[pep8speaks]

Hello @AndrewAnnex! Thanks for updating this PR. We checked the lines you've touched for PEP 8 issues, and found:

• In the file get_spice.py: No issues found.

• In the file setup.py: No issues found.

• In the file spiceypy/utils/libspicehelper.py: No issues found.

Comment last updated at 2021-10-20 17:29:47 UTC

[codecov[bot]]

Codecov Report

Merging #424 (5f30355) into main (73bba45) will decrease coverage by 0.02%. The diff coverage is 66.66%.

:exclamation: Current head 5f30355 differs from pull request most recent head c8ea43c. Consider uploading reports for the commit c8ea43c to get more accurate results

@@            Coverage Diff             @@
##             main     #424      +/-   ##
==========================================
- Coverage   99.87%   99.85%   -0.03%     
==========================================
  Files          12       12              
  Lines       14750    14752       +2     
==========================================
- Hits        14732    14731       -1     
- Misses         18       21       +3     

Impacted Files	Coverage Δ
spiceypy/utils/libspicehelper.py	99.85% <66.66%> (-0.15%)	:arrow_down:
spiceypy/spiceypy.py	99.65% <0.00%> (-0.04%)	:arrow_down:

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[AndrewAnnex]

closing in favor of #428