QRhi GL backend should handle basic structs and arrays of struct in a uniform block

struct LightSource
{
    vec4  position;
    ...
};

layout (std140, binding = 1) uniform cbBufferLights
{
    int uNumLights;
    LightSource lights[MAX_NUM_LIGHTS];
};

struct LightSource {
    vec4 position;
    ...
}

struct cbBufferLights {
    int uNumLights;
    LightSource lights[16];
};

uniform cbBufferLights _N;