Get connectivity features' resting-state paradigm from configs

[AhmetNSimsek]

While the paradigm data is stored in the preconfigs, it was being replaced with the string "Resting State". The paradigm provides important information when it is provided, so this PR allows siibra to take it from the jsons.

[codecov-commenter]

Codecov Report

Merging #275 (75306e1) into main (5d8f673) will increase coverage by 0.13%.
The diff coverage is 37.38%.

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@@            Coverage Diff             @@
##             main     #275      +/-   ##
==========================================
+ Coverage   35.75%   35.89%   +0.13%     
==========================================
  Files          59       59              
  Lines        4984     5032      +48     
==========================================
+ Hits         1782     1806      +24     
- Misses       3202     3226      +24     

Impacted Files	Coverage Δ
siibra/configuration/factory.py	26.06% <0.00%> (ø)
siibra/core/concept.py	77.21% <ø> (ø)
siibra/core/region.py	40.32% <ø> (ø)
siibra/core/space.py	67.50% <ø> (ø)
siibra/features/basetypes/feature.py	34.90% <0.00%> (-0.34%)	⬇️
siibra/features/basetypes/regional_connectivity.py	21.29% <ø> (ø)
siibra/features/basetypes/tabular.py	30.00% <ø> (ø)
siibra/features/basetypes/volume_of_interest.py	41.93% <0.00%> (-2.19%)	⬇️
siibra/locations/point.py	26.92% <ø> (ø)
siibra/retrieval/datasets.py	48.43% <ø> (ø)
... and 14 more

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[xgui3783]

LGTM