* New interface method to iterate over dir entries
* Fix build and test failures from interface
* Fix entry iteration for StaticDirectory
* Make utility function for directory iteration
* Fix lint errors
* No wrapcheck on fs.ReaddirToIterate
* Be consistent for IterateEntry implementations
* Add StreamingFile interface
* unit test for virtualfs
* CLI: Snapshot create support for stdin sources
* Uploader support for fs.StreamingFile
* End to end test for stdin source snapshot
* upload test to improve coverage