Ensure the FilterNoDataVal GPU module can filter out NaN values

[kylebarron]

A NaN sentinel is not a value FilterNoDataVal can match (== is false for NaN by definition)

[kylebarron]

We can use

const FilterNaN = {
    name: 'filter-nan',
    inject: {
        'fs:DECKGL_FILTER_COLOR': `
      if (isnan(color.r)) { discard; }
    `,
    },
}