24 and 40 spriteSize in the js library.

[rhanmiano]

Hello, thank you for the awesome emoji toolkit.

Just wondering if there will be a change in the js library anytime soon to support 24x24 and 40x40 sprites? As I dig into the code, when sprites are turned on, the spriteSize is just constrained with '32' and '64' and cannot be overridden during any transformation methods like toImage.

In the PHP package, the client config can be set that's why we were able to use sizes other than '32' and '64' and use the '24' and '40' sprites that are included in emoji-assets. Hoping this could be possible in the JS library too.

Another question also, is there any plan to support ESM?

Happy to provide a PR also.