fix: adapter suite and memory adapter

[paulocoghi]

• fix: adapter suite and memory adapter with comparison weights similar to real databases
• refactor: humanize adapter suite and isolated the custom JSON encode/decode
• test: coverage for json_helper convenience methods

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (fd32ce9) to head (ffbfd6f).

Additional details and impacted files

@@            Coverage Diff            @@
##            master       #29   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           34        35    +1     
  Lines         1137      1146    +9     
  Branches         4         4           
=========================================
+ Hits          1137      1146    +9     

Flag	Coverage Δ
unittests	100.00% <100.00%> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
src/adapter/memory.cr	100.00% <100.00%> (ø)
src/alumna.cr	100.00% <ø> (ø)
src/core/json_helper.cr	100.00% <100.00%> (ø)
src/http/serializers/json_serializer.cr	100.00% <100.00%> (ø)
src/testing/adapter_suite.cr	100.00% <100.00%> (ø)