Sync tests with problem specs

[simisc]

[no important files changed]

Protein translation

Explicitly skipped four missing test cases as per #245 and forum discussion.

Added one missing test case. All published solutions pass the additional test.

Reverse string

Explicitly skipped test cases that depend on Unicode support.

Roman numerals

Added one missing test case. This is not expected to break any existing solutions, because the stub file specifies the required output length.

[github-actions]

This PR touches files which potentially affect the outcome of the tests of an exercise. This will cause all students' solutions to affected exercises to be re-tested.

If this PR does not affect the result of the test (or, for example, adds an edge case that is not worth rerunning all tests for), please add the following to the merge-commit message which will stops student's tests from re-running. Please copy-paste to avoid typos.

[no important files changed]

For more information, refer to the documentation. If you are unsure whether to add the message or not, please ping @exercism/maintainers-admin in a comment. Thank you!

[github-actions]

Hello 👋 Thanks for your PR.

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