Add option to set UILaunchStoryboardName in Info.plist from MSBuild

[Redth]

Currently MAUI is relying on generating a partial Info.plist file and including that file in the build for things like:

• Fonts (now obsolete)
• Launch Storyboard
• App Icon (planned - separate issue)

Recently support was added for registering Fonts in the Info.plist in the core macios SDK targets.

There's still a couple of areas left that would be nice to specify as MSBuild properties or items so that we didn't need to spin up a whole separate task for including these in the Info.plist - which while not significant, would slightly help build times, since the ios sdk already is writing a file for this.

We need to set:

• <key>UILaunchStoryboardName</key><string>[Storyboard File]</string>

Could we have an MSBuild property for setting this file such that it gets included appropriately in the Info.plist?