Add pkg/sqlutils/models and pkg/utils/tests/json.go from core repo

[reductionista]

This moves some chain agnostic types out of chainlink into here, so they can be used by more than just that repo. See linked PR

Resolves Dependencies

• https://github.com/smartcontractkit/chainlink/pull/13881

[jmank88]

Let's find a better place than package models: https://go.dev/blog/package-names

What about the existing sqlutil package?

[github-actions[bot]]

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