Use async clipboard api [1] over this dependency, saving around 10kB
bundle size before minify while delivering the same functionality.
The issue comment button works but does not have a popup indication. We
could add some toast-style notifications in the future to fix that but I
think it's out of scope of this PR.
[1] https://developer.mozilla.org/en-US/docs/Web/API/Clipboard/writeText
The four clone button templates are pretty much identical except the one
in a non-empty repo had a few features which the others lacked.
Consolidate them in a single shared template which also makes the JS
that remembers protocol work on them all.
Co-authored-by: techknowlogick <techknowlogick@gitea.io>
