Implement QtQuick bindings for Sonnet

Still lot of TODOS:

• Need to open a related MR in QQC2-Desktop-Style to use it.
• Make it configurable with attached properties so that applications can opt-in into spellchecking.
• Add examples so that non QQC2-desktop-style based applications can also use it.
• Add bindings for options, dictionary, and other stuff existing the widgets word...
• Make the remaining setting writable

• Split Gui stuff from Quick stuff and add some todo to make the widget stuff depends on the gui stuff :)