Enhancement: ProtobufFactory

Nobody has claimed this yet.

### Summary

We use protobuf extensively in our python applications, and it would be super handy to be able to generate randomised test messages that conform to our protobufs.

### Basic Example

The usecase for this seems kind of obvious and I'm not sure if I can provide a better example than this. Happy to add more if you can direct me what would be more useful.

```python
from schemas.my_protobuf_message_pb2 import MyProtobufMessage

class MyProtobufMessageFactory(ProtobufFactory[MyProtobufMessage]): ...
```

### Drawbacks and Impact

Drawback is probably maintenance overhead and version support. Protobuf's internal API isn't the most stable in the world and new versions consistently break things. On top of that , major version changes are generally quite disruptive, which means lots of users will be slow to update. Would probably need to maintain support for multiple protobuf versions. eg, right now the latest major release of protobuf is version 6, but the confluent schema registry python libraries still only support version 5.

### Unresolved questions

_No response_

Start by reviewing the existing factory entry points and the proposed ProtobufFactory[MyProtobufMessage] usage. Define how randomized messages should conform to generated protobuf types, then assess the required protobuf version support and compatibility expectations before implementation.

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