refactor: use ApplicationWindow as the main entry point

src/MainApplicationWindow.qml

src/calladapter.cpp

src/constant/JamiQmlUtils.qml

src/constant/JamiTheme.qml

src/conversationsadapter.cpp

src/lrcinstance.h

src/mainapplication.cpp

src/mainapplication.h

src/mainview/MainView.qml

src/mainview/components/AccountComboBox.qml

src/mainview/components/AccountComboBoxPopup.qml

src/mainview/components/CallOverlay.qml

src/mainview/components/CallStackView.qml

src/mainview/components/ConversationSmartListView.qml

...view/components/ConversationSmartListViewItemDelegate.qml

src/mainview/components/MessageWebView.qml

src/mainview/components/UserInfoCallPage.qml

src/mainview/components/WelcomePage.qml

src/settingsview/SettingsView.qml

src/settingsview/components/KeyBoardShortcutTable.qml