chore: Warnings break build (#7734)

* Add "-D warnings" to relevant Github Actions workflows

This commit adds "-D warnings" to relevant Github Actions workflows, ensuring
that the build will fail if we leave any warnings present in the project.

Resolves #7733

Signed-off-by: Brian L. Troutwine <brian@troutwine.us>

* Remove warnings-as-error for just benchmark

Signed-off-by: Brian L. Troutwine <brian@troutwine.us>