Emancipation Checklist api set status code to 500 for errors

[FireLemons]

Description When an error occurs for emancipation ajax requests, send the correct HTML Status codes 400s (client errors) 500s (server errors) The emancipation javascript expects to receive errors as 200s range status codes (success) update how errors are handled in app/javascript/src/case_emancipation.js update tests

More about HTML status codes here: https://developer.mozilla.org/en-US/docs/Web/HTTP/Status

[compwron]

@FireLemons can you add more details to what change we want to make here?

[dpaola2]

@GALTdea @ThomasNathan