oav tool output of `oav validate-example` is not JSON

## Issue Description
The output of invoking `oav validate-example -l json -f out.json` is not a valid json.

For example: When running oav tool on the folder below:
[swagger.zip](https://github.com/Azure/oav/files/10007053/swagger.zip)

```bash
oav validate-example swagger/specification/applications/resource-manager/Applications.Core/preview/2022-03-15-privatepreview/applications.json -l json -f out.json
```

See how the resutling values in `out.json` are not valid json by trying to consume this using `jq`

## Additional Info

Valid json has double quoted properties and values and each object should be in a json array separated by commas.