Fix CSS scale handling by passing through mjolnir.js event data

[rjwats]

This PR fixes incorrect screen coordinate calculation in EditableLayer by using the offsetCenter provided by mjolnir.js gesture events, instead of recomputing coordinates from the DOM event (clientX/Y + canvas bounds).

I've also tightened up the types in editable-layer.ts, there are a lot of events typed as any which this tries to address too.

Some local manual testing done, no tests written yet - raising to get initial thoughts on this approach.

[rjwats]

I've added a unit test for the abstract class which this PR updates. It's so heavily integrated with deck.gl and mjolnir.js that there's a lot of mocking needed to exercise the code.. maybe there's a better way to test this?

[rjwats]

To locally test this you can add this div around the DeckGL element in advanced editor example:

<div
        style={{
          transform: 'scaleX(1.2) scaleY(0.8)',
          transformOrigin: 'center',
          width: '100%',
          height: '100%'
        }}
      >
        <DeckGL>.... </DeckGL>
</div>

Behavior before the fix:

before.mp4

Behavior after the fix:

after.mp4