Add a way to see my access token

I would love to have a button at the bottom of settings to copy my access token to the clipboard. Had a small emergency with my server today and needed to access the admin API but I only had my iPad with me and as far as I can tell there is no way to see your access token in Riot iOS.

Start at the iOS Settings screen and inspect how account actions and clipboard interactions are implemented. The work is done when a user can access and copy their access token from the bottom of Settings, with the behavior verified on iPad.

Written by the indexing model from the issue text.