Allow to use export advanced with selection only

[BoKKeR]

• I agree to follow the Code of Conduct that this project adheres to.
• I have searched the issue tracker for a feature request that matches the one I want to file, without success.

Is your feature request related to a problem? Please describe.
The default export for PDF and PNG supports exporting only the selection. The problem is that I would like to adjust the size of the export, since the PDF gets broken into many smaller pdf-s when exported at 100%. This can only be done in the advanced export. Which does not support exporting selection only

Describe the solution you'd like
I would like to have the option to export only selection from the advanced page

Describe alternatives you've considered
An alternative is copying all the content to a new page and exporting that with advanced.

Additional context
I tried this only on desktop draw.io!