FIX - "execute_if" setting to run hook after import failed in wcst_import

[Bang Pham Huu]

Currently, hooks in ingredients file run only when files imported successfully.
However, it is also useful when the hooks run when files failed to import. Use case, to move / rename the failed import files.

So hooks will have a new setting, called executed_if with one of values: import_succeeded (default) or import_failed)

For example:

    {
      "description": "Remove imported files.",
      "when": "after_import",
      "execute_if": "import_failed",
      "cmd": "rm -rf \"${file:path}\""
    }