Add method overloading

[roman-khimov]

neo-project/neo#2237, we now can have methods with identical names, but different number of parameters and we need to choose an appropriate one for the call.

[fyrchik]

I haven't come up with how we can support this in compiler and it's not Go-way, so may be only interop handling should be changed. Essentially, ...interface{} varargs do the same work.

[roman-khimov]

The only thing we need from the compiler is to generate correct code for deploy(1,2) and deploy(1,2,3) calls, of course our contracts won't expose any overloaded methods.