[WIP] Implement ServiceCall exception logging using HttpErrorHandler interface

[yakovlevdmv]

Pull Request Checklist

• Have you read through the contributor guidelines?
• Have you signed the Lightbend CLA?
• Have you added copyright headers to new files?
• Have you updated the documentation?
• Have you added tests for any changed functionality?

Fixes

Fixes #1091, #1375, #1398

Purpose

Provide the opportunity to override the ServiceRouter's exception logging.
The concept described in #1398:

... this part of the code shouldn't be handling errors at all, but let exceptions propagate up to be handled by the Play HttpErrorHandler...
-- @TimMoore

Todos:

• Implement custom HttpErrorHandler and move existing code into it
• Update the documentation
• Tests

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P.S. It's only the first version (PoC)

[TimMoore]

There shouldn't be an Await here, as this will cause the thread to block. I believe the right way to do this would be to to replace recover above with recoverWith and return result.