GUI: U32: Fix compilation errors across entire project

After the initial changes just to scummvm/gui for u32, this commit includes the whole project

- Widget creations now always have u32 descriptions, labels, or tooltips
- Message dialogs make use of default arguments instead of providing the same argument explicitly
- encode String::format properly before passing on as argument where necessary
- Modify hugo utils (yesNoBox and notify box) to use u32
- Also provide fake constructors for the above which redirect to the u32 constructor
- Convert all keymap descriptions to u32 across all engines
- showConfirmationDialog in mohawk now uses u32
- showScummVMDialog also uses u32
- Scumm engine has dialogs now which use u32
- General fixes and wrapping convertToU32String for setLabels and related functions
- Add a fake constructor to MesssageDialog which redirects to the u32 constructor

engines/scumm/string.cpp

@@ -115,7 +115,7 @@ void ScummEngine::showMessageDialog(const byte *msg) {
 	if (_string[3].color == 0)
 		_string[3].color = 4;
 
-	InfoDialog dialog(this, (char *)buf);
+	InfoDialog dialog(this, Common::convertToU32String((char *)buf));
 	VAR(VAR_KEYPRESS) = runDialog(dialog);
 }