Implement NvAPI_GetAssociatedNvidiaDisplayHandle

[SveSop]

This is needed to get the NVIDIA Tech demo "Apollo 11 Lunar Landing Demo" running. Downloaded from here:
https://us.download.nvidia.com/downloads/cool_stuff/demos/Setup-Apollo-11-(1.05).exe

[SveSop]

Did not make any "tests", as i am .. uhm.. not sure how that works i guess.

[jp7677]

Thanks for the PR, very cool and straight forward, nice.

Wrt having a test, it should be very similar to https://github.com/jp7677/dxvk-nvapi/blob/master/tests/nvapi_sysinfo_topo.cpp#L191. In fact, it should look like:

    SECTION("GetAssociatedNvidiaDisplayHandle succeeds") {
        NvDisplayHandle handle1 = nullptr;
        NvDisplayHandle handle2 = nullptr;
        NvDisplayHandle handle3 = nullptr;
        REQUIRE(NvAPI_EnumNvidiaDisplayHandle(0U, &handle1) == NVAPI_OK);
        REQUIRE(NvAPI_EnumNvidiaDisplayHandle(1U, &handle2) == NVAPI_OK);
        REQUIRE(NvAPI_EnumNvidiaDisplayHandle(2U, &handle3) == NVAPI_OK);

        NvDisplayHandle handle;

        REQUIRE(NvAPI_GetAssociatedNvidiaDisplayHandle("Output1", &handle) == NVAPI_OK);
        REQUIRE(handle == handle1);

        REQUIRE(NvAPI_GetAssociatedNvidiaDisplayHandle("Output2", &handle) == NVAPI_OK);
        REQUIRE(handle == handle2);

        REQUIRE(NvAPI_GetAssociatedNvidiaDisplayHandle("Output3", &handle) == NVAPI_OK);
        REQUIRE(handle == handle3);

        REQUIRE(NvAPI_GetAssociatedNvidiaDisplayHandle("Output4", &handle) == NVAPI_NVIDIA_DEVICE_NOT_FOUND);
    }

Could you also please prefix the commit message with nvapi:?