Add support for new object types introduced in Workspace List API

[mohitraj007]

Recently the workspace list API seems to be returning new object types (FILE & REPO) (https://docs.databricks.com/dev-tools/api/latest/workspace.html#objecttype) (the type FILE is not listed here yet but we're seeing those in our API responses).
This library has only 3 file types as far as I can see, hence wanted to add support to the new types.
I can make a contribution too but just wanted to report the issue and get the opinion before moving forward.

[samshuster]

yes good catch. If you would be willing to contribute this change that would be helpful!