Add setting to choose MsgPack mode

```C#
internal enum MsgPackMode
{
Contract = 1, //StandardResolver
Contractless = 2, //ContractlessStandardResolver
Typeless = 3 // TypelessContractlessStandardResolver
}
```
I don't know how to do it right now, becaus I have to call `CompositeResolver.RegisterAndSetAsDefault` in a static constructor

Start by examining the static constructor and its call to CompositeResolver.RegisterAndSetAsDefault. Determine how the requested MsgPackMode setting should select Contract, Contractless, or Typeless behavior, and consider how completion can be verified for each mode.

Written by the indexing model from the issue text.