This commit adds several fixes and improvements for the Zig compiler
test harness.
1. -Dskip-translate-c option added for skipping the translate-c tests.
2. translate-c/run-translated-c tests in test/cases/* have been added to
the steps test-translate-c and test-run-translated-c. Closes#18224.
3. Custom name added to the CheckFile step for the translate-c step to
better communicate which test failed.
4. Test manifest key validation added to return an error if a manifest
contains an invalid key.