[#118] Fix unsafe Json http api data instances

[Kariel-Myrr]

Description

Problem:

FieldName, EntryTag, PathSegment 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

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