[editor] Export result "Save" button should be disabled required fields are empty

When user tries to export query result for hive query or impala query.

"Save" button should be disabled before user fills in the mandatory field. (path/to/filename or new table name)

For now, without entering any text, user is able to "Save" it which leads a "500" server error or other errors.

We should do input validation to avoid these errors.