- admin flag exposed to qml for chat/channel
- `CreateChannelPopup` updated
- `createPopup` function added to the `Global` singleton
- `PinnedMessagesPopup` component moved to `AppMain` and shared
among components beneath
The openPopup function was declared in AppMain
and used via dynamic scoping in many places in the
application. Moved function to Global component
and updated all places to call it via Global instead.
Closes#4267