Enhancement: Make clipboard copy available to more browsers

We have added more functionality for copying (e.g. links) to the user's clipboard.
By switching libraries we now use the standard browser API (if available) with a
fallback and only offer copy-to-clipboard buttons if the browser supports it.

https://github.com/owncloud/web/pull/8136
https://github.com/owncloud/web/pull/8173
https://github.com/owncloud/web/issues/8134
