Switch all D2D1 interface methods (except bytecode) to properties

[Sergio0694]

Description

This PR switches all D2D1 interface methods to be properties instead (HLSL bytecode pending another PR):

namespace ComputeSharp.D2D1.__Internals;

public interface ID2D1Shader
{
    D2D1PixelOptions PixelOptions { get; }
    int InputCount { get; }
    D2D1BufferPrecision BufferPrecision { get; }
    D2D1ChannelDepth ChannelDepth { get; }
    string HlslSource { get; }
}