[#118] Fix unsafe Json http api data instances

[Kariel-Myrr]

Description

Problem:

FieldName used unsafe(default text) constructors for FromJSON, FromJSONKey and FromHttpApiData

Solution:

Write new safe instances that use smart newFieldName constructor. Cover new functionality with bad-case tests Also corrected previous Error msg.

Related issue(s)

Fixed #118

:white_check_mark: Checklist for your Pull Request

Related changes (conditional)

• Tests

  • [x] If I added new functionality, I added tests covering it.
  • [ ] If I fixed a bug, I added a regression test to prevent the bug from silently reappearing again.

• Documentation

  • [ ] I checked whether I should update the docs and did so if necessary:
  • README
  • Haddock

Stylistic guide (mandatory)

• [x] My commits comply with the policy used in Serokell.
• [ ] My code complies with the style guide.