Port from codec-argonaut to codec-json

[f-f]

Followup to purescript/registry-dev#690 - in this PR we port the JSON decoding from codec-argonaut to the new codec-json, in order to improve error messages.

This fixes #1057, as now the error message for missing license is much more readable:

Reading Spago workspace configuration...

❌ Couldn't parse Spago config, error:


  $.package.publish.license: No value found

And this fixes #1090, as we are now able to get errors through when parsing strings. E.g. an invalid PackageName now reports the reason:

Reading Spago workspace configuration...

❌ Couldn't parse Spago config, error:


  $.package.name: Package name cannot be longer than 150 characters