Move ImplInitAppFontData from Window to Application

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().

Change-Id: I9d98aa5b533166f91352218af267930034648c7a
Reviewed-on: https://gerrit.libreoffice.org/9242
Reviewed-by: Chris Sherlock <chris.sherlock79@gmail.com>
Tested-by: Chris Sherlock <chris.sherlock79@gmail.com>