I have renamed ImplInitAppFontData to InitAppFontData and moved it from
Window to Application. This is because this is something that sets
*application* global variables, it just so happens it gets it from a
Window parameter. But it should be set when the application starts, so I
have moved it to Main().

This was previously reverted, but I have since located what was causing
unit tests to fail and the font dropdowns to stop loading in writer:
see commit c6d7ba5f33c3 where Application::SetSettings() was setting
pImplSVData->maGDIData.mnAppFontX to zero.

Change-Id: I5da7073b0d8541f1a71a09b0a8337d012fc4134b