fix: NetworkBehaviours with inheritance are failing to sync public NetworkVariables

[JayPeet]

If you have a class

class A : NetworkBehaviour
{
    private NetworkVariable<int> TestA = new();
    public NetworkVariable<int> TestB = new();
}

and a subclass

class B : A
{
    public NetworkVariable<int> TestC = new();
}

When a NetworkObject with B attached is spawned, Only the private fields on the parent class A will be initialized correctly and sent across the network. TestA and TestC will send fine. TestB will not get its NetworkBehaviour set and wont send.

Testing and Documentation

• No tests have been added. But we might be able to add a test to validate this situation?

[0xFA11]

thank you for finding the issue and offering a fix.
based on your PR, I did other required legwork (tests, changelog) with a bit of refactor and put it up for review.

so, this PR is superseded by #2423