Support typescript for node object

[ofir-rifo]

Thanks for awesome library 😁
I created a custom eslint rule using this package to lint json files.

I have similar code to what you have in this file lib/rules/key-name-casing.ts
return { JSONProperty(node) {

But my code doesn't recognize the node type and I need to use any.
Can you please add types ?

[ota-meshi]

I'm not sure what needs to be exposed to get it to type check properly.
Would you consider opening a PR?