ui: add copy path button to file view (#6079)
Port of https://github.com/go-gitea/gitea/commit/d11f8d24b0cd6b5a508df43c9e0912713cad9ce7.
Followup to https://codeberg.org/forgejo/forgejo/commit/187e10d8c9d8cd3edeb953e520ba370f2f1c73b3.
* removed `aria-label` in the diff template
* changed `Copy to clipboard` to `Copy path`
* left `copy_generic` for now, but it's unused
* ported the addition of this button to the file view template
Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/6079
Reviewed-by: Otto <otto@codeberg.org>
Co-authored-by: silverwind <me@silverwind.io>