Create conversation without participants should be allowed

[SystemKeeper]

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Steps to reproduce

1. Create a new conversation
2. Select "Open for registered users"

Expected behaviour

Left button to directly create the conversation should be visible (as is when it's a public link)

Actual behaviour

Talk app

Talk app version: main

[SystemKeeper]

Suggestion from @nickvergessen: Maybe we should just show the button always, in case you want to prepare a meeting and post files, etc.