feat(model): add test command

[rhamzeh]

Description

• Add model test command
• Update Readme
• Friendlier output of model test
• Sort before comparing response arrays from list objects

To test:

• make build
• ./dist/fga model test --file example/model.fga --tests example/tests.fga.yaml to write and test a model
• ./dist/fga model test --tests example/tests.fga.yaml to test a previously written model
• ./dist/fga model test --tests example/tests.fga.yaml --verbose to see the full JSON output

References

Closes #136

Review Checklist

• I have clicked on "allow edits by maintainers".
• I have added documentation for new/changed functionality in this PR or in a PR to openfga.dev [Provide a link to any relevant PRs in the references section above]
• The correct base branch is being used, if not main
• I have added tests to validate that the change in functionality is working as expected