[Breaking Change] Runtime exceptions aggregate

Note: the list below is competing for priority with
- https://github.com/Azure/azure-sdk-tools/issues/7795

This is an aggregate issue for Breaking Change runtime exceptions:

- [ ] https://github.com/Azure/azure-sdk-tools/issues/5981
- [ ] https://github.com/Azure/azure-sdk-tools/issues/6036
- https://github.com/Azure/azure-sdk-tools/issues/6998
- [ ] https://github.com/Azure/azure-sdk-tools/issues/6168

And from the old, pre-transfer backlog:

- https://github.com/Azure/openapi-diff/issues/271
- https://github.com/Azure/openapi-diff/issues/258
- https://github.com/Azure/openapi-diff/issues/241
- https://github.com/Azure/openapi-diff/issues/239

Related issue:
- https://github.com/Azure/azure-sdk-tools/issues/6859

## Errors reported after 9/11

I.e. after the [runtime exception fix got merged](https://devdiv.visualstudio.com/DevDiv/_git/openapi-alps/pullrequest/496834) and deployed.

- https://github.com/Azure/azure-sdk-tools/issues/6998
- https://github.com/Azure/azure-sdk-tools/issues/6999

## References

For more, see comments below.

Konrad's private OneNote page for this issue is `#6169 [Breaking Change] Runtime exceptions aggregate`