Feature request: Save, Restore, Default buttons on repository dialog box.

[Clinton H]

1) Ubuntu 20.04
2) Synaptic 0.84.6
3) In Synaptic, on the Repositories dialog box, could you add "Save", "Restore", and "Default" buttons? Clicking the Save button would save to a file all the repository listings. Clicking the Restore button would replace the listed repositories with repositories listed in the saved repository file. Clicking the Default button would replace all the listed repositories with the default Synaptic issued repositories.
4) If an important repository is deleted, there is not an easy way to restore it.