Static pin feature

[elliottkember]

When using this component as a map location picker, it can be useful to identify a fixed location as a "pin", and move the map around underneath that pin to choose a location. It's a very common pattern for choosing a location.

This feature adds the following props to the component:

  // The absolute location on the view of the static pin
  staticPinPosition?: {
    left: number;
    top: number;
  };
  // A custom pin element is possible
  staticPinIcon?: React.ReactElement;
  // Fired when the user stops dragging the map (chooses a position)
  onStaticPinPositionChange?: (position: Vec2D) => void;
  // Fired repeatedly as the user moves the map
  onStaticPinPositionMove?: (position: Vec2D) => void;
  // Whether to animate the pin, lifting it up while dragging
  animatePin: boolean;
  // Disable panning momentum on the map (an improved experience when selecting a location)
  disableMomentum: boolean;

Lifting and dropping the pin works best with a "pin" style icon (as in the default) - if you are using a crosshairs-style icon, it doesn't make as much sense.

Also included in this PR are the functions in src/helper/coordinateConversion.ts which we have found to be very helpful.

https://user-images.githubusercontent.com/42827/184237493-c0e862f0-5904-4290-8144-8b978de45b1b.mp4

[elliottkember]

~Note to self: noticed that the two-finger gesture no longer drags the image around when staticPin is not set.~

Fixed!

[thomasttvo]

I'm gonna merge this for now. We can revert or make updates if necessary