webview: add initial WebView support to the daemon

bin/dbus/cx.ring.Ring.PluginManagerInterface.xml

bin/dbus/dbusclient.cpp

bin/dbus/dbuspluginmanagerinterface.cpp

bin/dbus/dbuspluginmanagerinterface.h

configure.ac

meson.build

src/client/plugin_manager_interface.cpp

src/client/ring_signal.cpp

src/client/ring_signal.h

src/jami/plugin_manager_interface.h

src/meson.build

src/plugin/CMakeLists.txt

src/plugin/Makefile.am

src/plugin/jamipluginmanager.h

src/plugin/webviewhandler.h

src/plugin/webviewmessage.h

src/plugin/webviewservicesmanager.cpp

src/plugin/webviewservicesmanager.h