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ARROW-13689: [C#][Integration] Initial commit of C# Integration tests

cc @pitrou - if you want to take a first look. I'm not sure how to get the tests running locally yet, but I've run the integration app a few times against the 'primitive.json' file to test it out.

Closes #10973 from eerhardt/CSharpIntegrationTests

Authored-by: Eric Erhardt <eric.erhardt@microsoft.com>
Signed-off-by: Eric Erhardt <eric.erhardt@microsoft.com>