[deprecation] viewport-mercator-project was moved to @math.gl/web-mercator

When linking packages locally to develop on luma.gl and deck.gl, we've run into an issue where kepler.gl and other libraries don't agree on the version of `viewport-mercator-project` to use. When researching it I also found [on npm](https://www.npmjs.com/package/viewport-mercator-project) that this package is deprecated,
> On October 1, 2019 `viewport-mercator-project` was moved to `@math.gl/web-mercator`.

`kepler.gl` is currently pinned to `viewport-mercator-project@^6.0.0`. The version used by deck.gl 8.2.0 (the version used by kepler) is using [`"@math.gl/web-mercator": "^3.2.1"`](https://github.com/visgl/deck.gl/blob/e23c4c4cc3f289149ff3757ff63a7c48d398920a/modules/core/package.json#L38). I've also found that `react-map-gl 5.2.10+` uses `viewport-mercator-project@7.0.1`. Version 7 is just a re-export of `@math.gl/web-mercator`.

I'm curious if kepler.gl would accept a PR to replace `"viewport-mercator-project": "^6.0.0"` with `"@math.gl/web-mercator": "^3.2.1"`, the version used by deck.gl 8.2.0. [A search found](https://github.com/keplergl/kepler.gl/search?q=viewport-mercator-project) this package is used in some layers to scale things.