.Net: Fix for RestApiOperation.BuildQueryString

[markwallace-microsoft]

Motivation and Context

We have noticed few cases where API calls were failing. Sample response:

"errors":{"since_create_time":["The value '2024-05-01T00:00:00\u002B00:00' is not valid."],"before_create_time":["The value '2024-05-31T23:59:59\u002B00:00' is not valid."]}}

We are passing the value correctly to SK as 2024-05-01T00:00:00+00:00 but then it’s getting transformed to '2024-05-01T00:00:00\u002B00:00 in this code here.

Then in this particular API these arguments are passed in the URL. The final URL is this: /campaigns?before_create_time=2024-05-31T23%3a59%3a59%5cu002B00%3a00&since_create_time=2024-05-01T00%3a00%3a00%5cu002B00%3a00

Now, I believe the problem is that everything would work just fine if these values were passed as the request payload to the API, where API would deserialize it correctly. But, since these are passed in URL, the value is never deserialized and stays broken.

Description

Contribution Checklist

• The code builds clean without any errors or warnings
• The PR follows the SK Contribution Guidelines and the pre-submission formatting script raises no violations
• All unit tests pass, and I have added new tests where possible
• I didn't break anyone 😄