Warnings from generated code when nullable-reference types are enabled

[huynhsontung]

I am migrating from the legacy VS extension to the new ReswPlus source generator for a project with a nullable reference type enabled. On build, I got Cannot convert null literal to non-nullable reference type warnings in the generated code. I suspect the generated code does not support nullable-reference types. Many C# projects enforce nullable-reference checks to add extra safety when dealing with reference types, so having generated code to follow this convention is appreciated as well.

Warning in the build log: https://github.com/huynhsontung/Screenbox/actions/runs/14297107527/job/40065690346?pr=588#step:9:36917
Related PR: huynhsontung/Screenbox#588