ADFA-1322: Hide debugger overlay and bottom sheet tab when no VMs are connected (#293)

Updates the debugger toolbar and the debugger fragment lifecycle such that they are only visible as long a VM is connected to the debugger.

* fix: show debug overlay only when a VM is connected
* fix: show debugger fragment only when connection state >= ATTACHED

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Signed-off-by: Akash Yadav <akashyadav@appdevforall.org>

Author: itsaky-adfa