Keep copied_text

[rustbasic]

It's better to keep copied_text without deprecating it.
because there are cases where its content needs to be immediately retrieved and modified.

[github-actions]

Preview available at https://egui-pr-preview.github.io/pr/5540-patch155
Note that it might take a couple seconds for the update to show up after the preview_build workflow has completed.

[emilk]

Use PlatformOutput::commands instead

[rustbasic]

Use PlatformOutput::commands instead

My opinion is that it would be better to keep the current copied_text without deprecating it, rather than creating a new function to identify or modify the content on the clipboard.