Extract config loading

[groenroos]

Extract loading config, models, hooks, permissions, and controller into separate digest() methods, which only load and return the parsed, formatted, and validated object.

This helps the GUI use it independently, and ensure both load the same config the same way.

Closes #325

[codecov]

Codecov Report

Merging #414 (922c1e2) into master (1600646) will increase coverage by 0.02%.
The diff coverage is 99.30%.

@@            Coverage Diff             @@
##           master     #414      +/-   ##
==========================================
+ Coverage   98.24%   98.27%   +0.02%     
==========================================
  Files          37       37              
  Lines        4450     4516      +66     
==========================================
+ Hits         4372     4438      +66     
  Misses         78       78              

Impacted Files	Coverage Δ
core/loadHooks.js	98.83% <96.77%> (+0.26%)	⬆️
core/loadConfig.js	100.00% <100.00%> (ø)
core/loadController.js	100.00% <100.00%> (ø)
core/loadModel.js	100.00% <100.00%> (ø)
core/loadPermissions.js	100.00% <100.00%> (ø)

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