mpc fix, generate collect class name in nested enum.

[neuecc]

Currently mpc generate duplicate class name in nested enum.

public class Foo1
{
    public Bar Id { get; set; }

    public enum Bar
    {
        A
    }
}


public class Foo2
{
    public Bar Id { get; set; }

    public enum Bar
    {
        A
    }
}

// generate

class BarFormatter : IMessagePackFormatter<Foo1.Bar>
class BarFormatter : IMessagePackFormatter<Foo2.Bar>

I've modified generated type name from type.Name to type.ToDisplayString(ShortTypeNameFormat).Replace(".", "_").
It will generate

class Foo1_BarFormatter : IMessagePackFormatter<Foo1.Bar>
class Foo2_BarFormatter : IMessagePackFormatter<Foo2.Bar>

so solved.

Also csproj collector load duplicate version metadata such as MessagePack.dll, Version 2.0.90 and MessagePack.dll, Version 2.0.80.
It will fail GetTypeByMetadataName("MessagePack.MessagePackObjectAttribute").
This PR includes there fix to distinc by file name.