Changed share argument default in .launch method (#1449)
* changed default of share argument
* make share=False raise an Exception when localhost not reachable
* using self.share across the launch method
* reverted docstring to previous sentence
* added getter and setter for self.share
* added tests for setting Blocks.share
* fixed test
Co-authored-by: Abubakar Abid <abubakar@huggingface.co>
