Generic Importers - Destination Full Support

[calumcalder]

Background

Importers can signal failure for specific reasons with various subclasses of CopyExceptionWithFailureReason, some of which are treated as restartable errors. For example, InvalidTokenException and DestinationMemoryFullException signal a token expiry (which requires reauth and a restart) and a full destination (which requires the user to create space and restart) respectively.

Generic Importers (added in #1389) supports throwing InvalidTokenException on a 401 response with an invalid_token error from the API, but does not support DestinationMemoryFullException.

Proposal

To support destinations using Generic Importers creating a DestinationMemoryFullException, the API could be extended to define another error code and error name combination - e.g. 400 and destination_full. The Generic Importers code would then need to be extended to support handling this case.