Resource class overhaul

[munrojm]

This PR overhauls the the way resources are handled in the API. Specifically:

• Abstract base Resource class has been added
• Generic GetResource class added for standard GET endpoints
• Generic ConsumerPostResource class added for write-specific endpoints that handle consumer/user data
• Generic _post_resource method added to core client class to handle post requests

Additionally, a consumer settings endpoint has been added to allow writing consumer settings data.

[codecov-io]

Codecov Report

Merging #236 (882b3cd) into main (8554ac1) will decrease coverage by 1.59%.
The diff coverage is 0.00%.

@@           Coverage Diff            @@
##            main    #236      +/-   ##
========================================
- Coverage   3.00%   1.41%   -1.60%     
========================================
  Files        109     108       -1     
  Lines       3127    3119       -8     
========================================
- Hits          94      44      -50     
- Misses      3033    3075      +42     

Impacted Files	Coverage Δ
src/mp_api/bandstructure/resources.py	0.00% <0.00%> (ø)
src/mp_api/charge_density/resources.py	0.00% <0.00%> (ø)
src/mp_api/core/api.py	0.00% <0.00%> (ø)
src/mp_api/core/client.py	0.00% <0.00%> (ø)
src/mp_api/core/query_operator.py	0.00% <0.00%> (ø)
src/mp_api/core/resource.py	0.00% <0.00%> (ø)
src/mp_api/dielectric/resources.py	0.00% <0.00%> (ø)
src/mp_api/dois/resources.py	0.00% <0.00%> (ø)
src/mp_api/dos/resources.py	0.00% <0.00%> (ø)
src/mp_api/elasticity/resources.py	0.00% <0.00%> (ø)
... and 23 more

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