sbus_codegen_tests: Add test case type-safe handler args
    
    This adds a big test case for invoking a handler with all supported
    basic arguments, and constructing a reply with the same. Lots of
    tedious code, but worth it to make sure things work well.
    
    (cherry picked from commit 1203e462650f035b0df2304075d60b9a99e36715)