Wrap the display globals in a struct (#16998)

* Wrap the display globals in a struct

Makes it easier to search/replace these, for future refactorings.

* Some renaming

* Qt buildfix, also fix the Qt build on Mac (got broken with battery changes)

* Attempt at buildfixing ios

* UWP buildfix

Windows/Debugger/Debugger_MemoryDlg.cpp

@@ -257,7 +257,7 @@ void CMemoryDlg::Goto(u32 addr)
 
 void CMemoryDlg::Size()
 {
-	const float fontScale = 1.0f / g_dpi_scale_real_y;
+	const float fontScale = 1.0f / g_display.dpi_scale_real_y;
 
 	GetClientRect(m_hDlg,&winRect);
 	int dlg_w = winRect.right - winRect.left;