in-chat-view: allow toggling conversations list if space allows

[wiswedel]

On a spacious iPad tablet computer, toggling the conversations list should be possible while inside a chat, just like on desktop, so while being active in multiple conversations at the same time gets better managable.

[mario]

You must mean an Android tablet. Sure, definitely something to do in the far future (or earlier depending on the client).

[wiswedel]

You must mean an Android tablet.

Mixed up the repos, sorry. Of course, an Android tablet. Updating the OP.

[wiswedel]

related: nextcloud/talk-ios#302