add enum tag to jsonschema

[jtarchie]

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There is another issue, #912. It seems to have been abandoned.

Describe the change

When creating a JSON schema from a struct, a new tag enum can be used to see the Enum field.

For example,

type Car struct {
  Color string `json:"color" enum:"red,green,blue"`
}

This will see the Enum on the field definition would be Enum = []string{"red","green","blue"}.

This is implementation is being used.

Provide OpenAI documentation link
Provide a relevant API doc from https://platform.openai.com/docs/api-reference

Describe your solution

See change above.

Tests

1. A heads up, the tests on Github Actions are not running these tests. I've added support to this PR to ensure it runs correctly.
2. I've added tests for the enum field in the json_test.go. This also required adding some other tests for struct to schema definition.
3. Because of omitempty, I've updated the tests to reflect this.

Additional context
n/a

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 85.25%. Comparing base (774fc9d) to head (db50e2b).
Report is 88 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff             @@
##           master     #962       +/-   ##
===========================================
- Coverage   98.46%   85.25%   -13.21%     
===========================================
  Files          24       43       +19     
  Lines        1364     2259      +895     
===========================================
+ Hits         1343     1926      +583     
- Misses         15      312      +297     
- Partials        6       21       +15     

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[jtarchie]

I'm not sure why code coverage went down. Maybe adding more tests from Github Action?