Upgrade to .NET 10, expose ExcelPage and RowOffset

[Haselnussbomber]

In NotAdam/Lumina.Excel#11 we added ExcelPage and RowOffset properties to the generated sheet structs.
It would only make sense if we add those to the interfaces IExcelRow<T> and IExcelSubrow<T> too.

I had to rename the existing Page and Offset properties in RawRow and RawSubrow accordingly, which in turn also makes it much clearer what the offset is actually for.

Also updated:

• everything to .NET 10
• nuget dependencies
• Lumina.Example to use the new sheets system
• the CI workflow, but didn't touch the deprecated actions/create-release@v1 action.

But I can also remove those commits again, I don't mind either way.

[NotAdam]

sounds good to me, i'll try updating the create-release action for lols