RollCall Attendee Token needs Copy to Clipboard Button

[Kaz-ookid]

When attending a roll call, we get a QR code that can be scanned, holding our token. This token is also shown as a string under the QR, but is not selectable and thus not copyable. We need to make this token manually selectable, and we could also add a quick copy to clipboard button.

Basically, all the details and hints of implementation are the same as in #1853 :)

The token is to find following those steps:

1. Create a LAO on Device#1
2. Join the LAO on Device#2
3. Create and open a Roll Call on Device#1
4. Open the RollCall event on Device#2, that's it!