Add Api::ErrorHandling concern for api/base controller

[mjankowski]

This is a subset of #27925

• Includes JUST the extraction of the error handling methods into a concern, with zero modification to the controller code and as small a change as I could think of to the spec
• Does not include the i18n changes, the string method changes, or the spec refactor (to add response message check in addition to code checks) from the original

Will rebase that other and continue to pull out anything valuable (I think at least the string check in the specs is useful, even if the i18n and string method are not desired) from it if this is merged.