Convert MemoryBufferProtocolWrapper to generic

[BCSharp]

MemoryBufferProtocolWrapper was born out of a desire to provide a seamless and efficient conversion from CLR arrays (and Memory<byte> etc.) to IBufferProtocol, which proliferates the public API for "bytes-like" parameters.

It turns out that the wrapper class can be useful also for adapting Memory of other underlying unmanaged types to IBufferProtocol, hence the change to the generic MemoryBufferProtocolWrapper<T>. The rules in the conversion binder did not change, that is, still only byte-oriented types (byte[], Memory<byte>, ReadOnlyMemory<byte>) are eligible to be automatically converted by the ConversionBinder. However, C# code may now use the class for other conversions, therefore be able to call methods accepting IBufferProtocol using arrays/memory with other underlying types.