Fix featureIndex & featureSubIndex ordering in @turf/meta

[DenisCarriere]

Fixed featureIndex & featureSubIndex ordering

• Add GeometryCollection to Typescript definition
• Fix featureIndex & featureSubIndex ordering to coordEach & geomEach
• Refactor test.js

const data = featureCollection([
    point([0, 0]),
    lineString([[1, 1], [2, 2]]),
    multiLineString([[[1, 1], [0, 0]], [[4, 4], [5, 5]]])
]);

meta.coordEach(data, (coord, coordIndex, featureIndex, featureSubIndex) => {
  //=coordIndexes => [0, 1, 2, 3, 4, 5, 6]
  //=featureIndexes => [0, 1, 1, 2, 2, 2, 2]
  //=featureSubIndexes => [0, 0, 0, 0, 0, 1, 1]
});

meta.flattenEach(fcMixed, (feature, featureIndex, featureSubIndex) => {
  //=featureIndexes => [0, 1, 2, 2]
  //=featureSubIndexes => [0, 0, 0, 1]
});