Ability to add multiple waypoints at once

Nobody has claimed this yet.

It would be great if the plugin API could have a method like `addWaypoints()` to complement the existing `addWaypoint()` method. The reason for this is that displaying a route with multiple waypoints can result in rate limit issues as we are forced to do something like [simplified]:

```typescript
this.directions
.setOrigin(origin)
.setDestination(destination);

waypoints.forEach((waypoint, index) => {
this.directions.addWaypoint(index, waypoint); // a request each time
});
```

which results in multiple fast requests. This should be possible as the underlying directions API allows adding multiple points to a single request. So I suppose what I am asking to be possible is something like:

```typescript
this.directions
.setOrigin(origin)
.setDestination(destination)
.setWaypoints(waypoints);
```

Let me know if I have done something wrong or asked in the wrong place, and thanks for your time :)

Start by locating the existing addWaypoint() plugin API and follow how it builds and sends directions requests. Compare the requested addWaypoints() or setWaypoints() entry point with the underlying Directions API; done means multiple waypoints can be submitted in one request without repeated fast requests.

Written by the indexing model from the issue text.