AlwaysOnTop windows don't appear in the OSD

[ghost]

Easy to replicate, toggle any window AlwaysOnTop via the graphical client-menu and then Alt+Tab.
It happens with Wayland native programs and Xwayland as well. I only tested this on the lastest git master.
I believe this is a bug because the user cannot gain control back on the "OnTop" window.

[Consolatis]

Note about implementing a fix:
We might need to return to looping over server->views with a filter for node->parent being either the current workspace tree or the always-on-top tree. That should fix it.
It would also allow for a future rc.xml setting to show windows from all workspaces in A-Tab if set.

[Consolatis]

I actually intend to revert to using server->views + filter for current workspace (at least for A-Tab) because otherwise always-on-top views (and other non direct children of the workspace nodes) will not show up there (#856).

I had been thinking similar thoughts 😄
+possibly showing all workspaces in windowSwitcher? I know we said originally that we wouldn't but...
Preview would be hard I guess - but possibly not needed for other workspaces.

Originally posted by @johanmalm in #866 (comment)

Good point regarding preview. Guess there is still some stuff to work out if we ever decide to add that config option.

[johanmalm]

COMPLETE
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