Consider ErrorHandlingMiddleware turning arbitrary errors into JSON error bodies

[czechboy0]

Motivation

See the discussion on this thread, we left it out of the implementation of SOAR-0011: apple/swift-openapi-runtime#126 (comment)

Proposed solution

We should consider it as an opt-in feature, similar behavior to Vapor (which enables it for debug only automatically).

Alternatives considered

No response

Additional information

No response