Feature id should accept type `number`

Nobody has claimed this yet.

mapbox-gl-draw provides a number of APIs that take a feature id as an argument or return it as a return value. Currently, the API documentation states that the `featureId` is a `string` value.

However, according to the GeoJSON specification, feature id can be a `string` or a `number`, so it seems odd that mapbox-gl-draw does not consider id of type `number`.

> If a Feature has a commonly used identifier, that identifier SHOULD be included as a member of the Feature object with the name "id", and the value of this member is either a JSON string or number.
> https://datatracker.ietf.org/doc/html/rfc7946#section-3.2

From the little testing I did at hand, there seemed to be no problem with mapbox-gl-draw operation even if a feature had an id of type `number`, but is there a reason why the current API documentation only specifies an id of type `string`? Also, is there any consideration to officially support id of type `number`?

Start by locating the API documentation and implementation or type declarations that define featureId as a string, then inspect the related feature-id usages and tests. Done means the supported type matches the GeoJSON string-or-number requirement and the API documentation and relevant tests reflect that support.

Written by the indexing model from the issue text.