Fix type parsing of type names with generic array parameter

[ReubenBond]

Fixes #8330

This is a generics corner case which was stumping the type parser when parsing a formatted unconstructed generic type.
For example, this type would not round-trip successfully:
typeof(List<>).MakeGenericType(typeof(Inner<>.Middle).MakeArrayType())

Concretely, this behavior was being hit when compiling the grain manifest for a type like IGenericArrayRegisterGrain<T>, since the manifest would contain the implemented interfaces, which contains IGenericRegisterGrain<T[]> (with no concrete T):

public interface IGenericRegisterGrain<T> : IGrainWithIntegerKey
{
  Task Set(T value);
  Task<T> Get();
}

public interface IGenericArrayRegisterGrain<T> : IGenericRegisterGrain<T[]>
{
}

The fix is to check that we are indeed looking at a formatted generic type, versus an array, by reading ahead for the presence of [[ (indicating a generic parameter list) rather than just [ (ambiguous between an array specification or generic parameter list)

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