Copy of values (to clipboard)

[optout21]

I planned to make an easier way to copy the resulting delegation tag. I've tried:

• Display in a Text, multi-line. However, selection and copy is not supported in Text.
• Display in TextInput multi-line: apparently TextInput does not support multi-line
• Add a Copy button, using clipboard::write, but unfortunately that did not work.

Hence for now it can be copied only by selecting all in the single-line readonly TextInput, and Ctrl-C. To check with iced how to solve Copy button.