Provide early, friendly error reporting for invalid record use after OutputComplete

[llvm-beanz]

Evaluate the ability to provide earlier (AST-level) diagnostics for invalid record use after OutputComplete. This could be modeled after clang diagnostics for use after std::move.

[pow2clk]

Error already exists in validation. It would be nice to have it earlier, but there might be more important tasks for 6.8

[damyanp]

Plan is to address this in clang.