chore: stronger typing for xast/css-select code

[SethFalco]

Significantly improves type checking for lib/svgo/css-select-adapter.js. Before, we declared an explicit any over the options.

• No longer declares the type of querySelector and querySelectorAll in our .d.ts file. Instead, we use a JSDoc type, and export that in our .d.ts. This achieves the same result, but we maintain the type with the implementation, leaving less risk for it to fall out of sync.
• Deletes lib/svgo/css-select-adapter.d.ts and uses the upstream types when we define our config. (I did declare any for two functions as they were annoying to resolve, I will look at this in future. Again, I'm striving for better, not perfect.)