feature: allow calling [Command]s on server-only directly. #3450

[miwarnec]

NEW PLAN

MrG:
Command(allowServerCall = true)]

---

TODO

• IL2CPP builds still fail
• test coverage
• try in assets: ummorpg and replace the old wrappers
• reset changes to Tanks.cs
• change to isServer / is Client?
• uMMORPG: PlayerParty [Command] wrappers removed. editor=host, build=client, host invites client to party, client closes. warning: "Command Function System.Void PlayerParty::CmdDismiss() called on y without authority."

calling [Command] on server-only gives the following error:

Command Function System.Void Mirror.Tests.RemoteAttrributeTest.AuthorityBehaviour::SendInt(System.Int32) called on New Game Object without an active client.

before:

    [Command]
    private void CmdTest(int value)
    {
        NetworkWriterPooled writer = NetworkWriterPool.Get();
        writer.WriteInt(value);
        SendCommandInternal("System.Void Mirror.Examples.Tanks.Tank::CmdTest(System.Int32)", 897081557, writer, 0);
        NetworkWriterPool.Return(writer);
    }

    public override void OnStartServer()
    {
        CmdTest(42);
    }

after:

    [Command]
    private void CmdTest(int value)
    {
        if (NetworkServer.active && !NetworkClient.active)
        {
            UserCode_CmdTest__Int32(value);
            return;
        }
        NetworkWriterPooled writer = NetworkWriterPool.Get();
        writer.WriteInt(value);
        SendCommandInternal("System.Void Mirror.Examples.Tanks.Tank::CmdTest(System.Int32)", 897081557, writer, 0);
        NetworkWriterPool.Return(writer);
    }

    public override void OnStartServer()
    {
        CmdTest(42);
    }

use cases in ummorpg. before:

    // version without cmd because we need to call it from the server too
    public void Leave()
    {
        // try to leave. party system will do all the validation.
        PartySystem.LeaveParty(party.partyId, name);
    }
    [Command]
    public void CmdLeave() { Leave(); }

    // version without cmd because we need to call it from the server too
    public void Dismiss()
    {
        // try to dismiss. party system will do all the validation.
        PartySystem.DismissParty(party.partyId, name);
    }
    [Command]
    public void CmdDismiss() { Dismiss(); }

[miwarnec]

CmdOnAnimationServerMessage still fails to weave properly:

[Command]
private void CmdOnAnimationServerMessage(int stateHash, float normalizedTime, int layerId, float weight, byte[] parameters)
{
    //IL_001b: Expected O, but got I4
    //IL_001b: Expected F4, but got O
    if (NetworkServer.active && !NetworkClient.active)
    {
        ((NetworkAnimator)/*Error near IL_001b: Stack underflow*/).UserCode_CmdOnAnimationServerMessage__Int32__Single__Int32__Single__Byte[]((int)/*Error near IL_001b: Stack underflow*/, (float)/*Error near IL_001b: Stack underflow*/, (int)/*Error near IL_001b: Stack underflow*/, (float)this, (byte[])stateHash);
        return;
    }
    NetworkWriterPooled writer = NetworkWriterPool.Get();
    writer.WriteInt(stateHash);
    writer.WriteFloat(normalizedTime);
    writer.WriteInt(layerId);
    writer.WriteFloat(weight);
    writer.WriteBytesAndSize(parameters);
    SendCommandInternal("System.Void Mirror.NetworkAnimator::CmdOnAnimationServerMessage(System.Int32,System.Single,System.Int32,System.Single,System.Byte[])", -1895293543, writer, 0);
    NetworkWriterPool.Return(writer);
}