chore(enrichment tables): wrap enrichment errors in a custom type

[gwenaskell]

Summary

The error type returned from the enrichment::Table trait methods results is a plain string which does not help to check if the lookup error is either caused by an invalid input, a row not found or multiple rows found. This PR wraps it in an enum which makes this explicit.

How did you test this PR?

unit tests

Change Type

• Bug fix
• New feature
• Non-functional (chore, refactoring, docs)
• Performance

Is this a breaking change?

• Yes
• No

Does this PR include user facing changes?

• Yes. Please add a changelog fragment based on our guidelines.
• No. A maintainer will apply the no-changelog label to this PR.

References

• Closes: #OPA-4299
• Related: #OPA-4226

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