[Breaking Change] Swagger Breaking Change PR check should highlight "NoVersionChange" for breaking changes to a preview

When the Swagger Breaking Change check detects breaking changes made to an existing preview -- but not breaking a prior GA -- the "NoVersionChange" message should be displayed as an error and all other messages as warnings.

A new preview (or GA) is allowed to break a prior preview, as long as this is done in a new API version, and when we see a case where the changes are made without bumping the api-version we always tell the team to make the change in a new api-version. So the report should highlight this.

An example is [PR #24452](https://github.com/Azure/azure-rest-api-specs/pull/24452):

In this case, the PR author _intended_ to remove the `type` property and add the optional `view` parameter, so flagging these as "errors" is not very helpful. And both are fine if the "NoVersionChange" "warning" is fixed. To guide service teams to this outcome, the "NoVersionChange" should be elevated to an error and any issues that would be allowed in a version should only be shown as warnings.