Move AVD Manager from Android Settings to Device Settings

Move AVD management and creation to Qt Creator's DeviceManager
facilities. This allows AVDs to be created from the Devices settings
page and their details and control/action buttons for starting/stopping,
etc. are added there as well. This makes the process similar to other
device types that Qt Creator supports, to get a similar experience.

Task-number: QTCREATORBUG-23991
Change-Id: I16c52b3cc73035e0ee12fd54ae9dad4595c8cda5
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Alessandro Portale <alessandro.portale@qt.io>

src/plugins/android/androidconfigurations.h

@@ -70,6 +70,7 @@ public:
     int sdcardSize = 0;
     QString error; // only used in the return value of createAVD
     bool overwrite = false;
+    bool cancelled = false;
 };
 
 struct SdkForQtVersions