Add a Show instance for Ordering

[cocreature]

Requested in
https://discuss.daml.com/t/why-isnt-ordering-an-instance-of-show-in-daml/1007
Seems like a very reasonable thing to have.

changelog_begin
changelog_end

Pull Request Checklist

• Read and understand the contribution guidelines
• Include appropriate tests
• Set a descriptive title and thorough description
• Add a reference to the issue this PR will solve, if appropriate
• Include changelog additions in one or more commit message bodies between the CHANGELOG_BEGIN and CHANGELOG_END tags
• Normal production system change, include purpose of change in description

NOTE: CI is not automatically run on non-members pull-requests for security
reasons. The reviewer will have to comment with /AzurePipelines run to
trigger the build.

[aherrmann-da]

Does this deserve a changelog entry?

[cocreature]

Does this deserve a changelog entry?

good point, I’ll add it on merging.

[hurryabit]

Makes a lot of sense. Thanks.