Lua TextureResource does not expose properties

It is impossible to read the path, offset, or size of the userdata returned from ui.texture(). This should be implemented for a better debugging experience.

Something like the following in uibindings.cpp

auto textureResource = context.sol().new_usertype<LuaUi::TextureResource>("TextureResource");

textureResource[sol::meta_function::to_string] = [](const LuaUi::TextureResource& resource) {
    return "TextureResource[" + std::string(resource.mPath.value()) + "]";
};

textureResource["path"] = sol::readonly_property([](const LuaUi::TextureResource& resource) {
    return std::string(resource.mPath.value());
});

textureResource["offset"] = sol::readonly_property([](const LuaUi::TextureResource& resource) {
    return resource.mOffset;
});

textureResource["size"] = sol::readonly_property([](const LuaUi::TextureResource& resource) {
    return resource.mSize;
});