CloudEvent validation fails due to strict encoding

With a few workarounds, I've managed to get the .NET CloudEvent function to *nearly* meet validation - but the validation framework expects the mediaLink to be exactly:

```json
"https://www.googleapis.com/download/storage/v1/b/some-bucket/o/Test.cs?generation=1587627537231057\u0026alt=media"
```

... whereas my output is:

```json
"https://www.googleapis.com/download/storage/v1/b/some-bucket/o/Test.cs?generation=1587627537231057&alt=media"
```

Given that they're *equivalent* JSON, I believe it would be okay for the test to pass here. Perhaps validation tests that expect JSON should "parse and reformat" both input and output before comparing?