* cli: added 'repository validate-provider' which runs a set of tests against blob storage provider to validate it
This implements a provider tests which exercises subtle behaviors which are not always correctly implemented by providers claiming compatibility with S3, for example.
The test checks:
- not found behavior
- prefix scans
- timestamps
- write atomicity
* retry: improved error message on failure
* rclone: fixed stats reporting and awaiting for completion
* webdav: prevent panic when attempting to mkdir with empty name
* testing: run providervalidation.ValidateProvider as part of regular provider tests
* cli: print a recommendation to validate provider after repository creation
