Add support for Instance Owner access option in the access controls

[orels1]

We can use VRCPlayerApi.isInstanceOwner to check that.

Networking.IsInstanceOwner always returns true, so don't use that!

Could be just another option in the list of checkboxes. Should probably rename the Owner to Object Owner to clarify

[towneh]

I'm currently using the following as a working alternative to the broken Networking.IsInstanceOwner:

if (Networking.LocalPlayer.isInstanceOwner) {

(be careful to use the lowercase "is")