OpenAPI-diff should flag changes in the tags for an operation

Some tooling uses the operation tags to group or namespace the operations in an API definition. SwaggerUI is one example, but many other tools do as well.

For this reason, OpenAPI diff should detect and report any change in the array of tags specified for an operation. The message should be a warning since this change does not impact the "on the wire" behavior of the API.

A real-life example that tripped up Terraform generation is [#34736](https://github.com/Azure/azure-rest-api-specs/pull/34736).