feat: Improve access to simulator parameters

[simon-lemay-unity]

MTT-2619

This PR offers a cleaner way to manage the simulation pipeline parameters. There's now a dedicated section in the inspector for these parameters, and a dedicated method to set them (SetDebugSimulatorParameters). All of this used to be available already, but it was not very discoverable (editor preferences when in the editor, public fields in development builds) and was inconsistent with how other parameters are managed. The PR maintains backwards compatibility with these mechanisms.

Changelog

com.unity.netcode.adapter.utp

• Added: New parameters are available to simulate network conditions (delay, jitter, packet loss) in the editor and in development builds. The parameters are available under the 'Debug Simulator' section of the 'Unity Transport' component, or can be set with the SetDebugSimulatorParameters call.

Testing and Documentation

• Includes unit/integration test.
• No documentation changes or additions were done. Could be interesting to update the public documentation.