Add copy to clipboard button for setup strings

[mirenz1]

Add a copy to clipboard function to the setup string text fields, so that the setup string can be easily copied to the clipboard with one click.

• [ ] Setup string can be copied to clipboard with one click

[mbfm]

Discussion how to realize this: https://github.com/leptos-rs/leptos/discussions/2399 (Feature is not anymore unstable.)

[voelkera]

Suggestion for button layouts

[voelkera]

[mbfm]

Implemented in #299.