Allow to override Endpoint url method to handle objects in query params

[uxxman]

Is your feature request related to a problem? Please describe.
Currently, this lib doesn't handle using deeply nested objects as query params. We need a way to allow the users to handle this on their own. As discussed here #348

[ntucker]

On holidays ATM; but I will look at this end of week. Should be pretty easy. Thanks for the report!

[uxxman]

no worries 😉 have a great week

[ntucker]

Example implementation using qs library for search parameter serialization

import { RestEndpoint, RestGenerics } from '@data-client/rest';
import qs from 'qs';

class QSEndpoint<O extends RestGenerics = any> extends RestEndpoint<O> {
  searchToString(searchParams) {
    return qs.stringify(searchParams);
  }
}

Released in 0.10