SimpleOffsetPaginator fix and Json Selector

[BubbaTLC]

Hello,

This is my first contribution so please give me feedback.

I was attempting to use the new SimpleOffsetPaginator implemented here #48. I encountered a bug in streams.py as the pagination_page_size was not being properly set, so I was unable to specify a different value other than 25. I believe this issue was introduced when trying to fix a different issue in #52

I have also added the ability to select the records in the request, to enable counting of nested records.

My API was returning records like the example I gave in the readme which gave me a count of 2 no mater how many records are in the contacts list.

  {
    "contacts": [
      {
        "id": 52,
        "emailBlacklisted": false,
        "smsBlacklisted": false,
        "createdAt": "2024-09-24T01:00:00.000-00:00",
        "modifiedAt": "2024-09-25T01:00:00.000-00:00",
      }
    ],
    "count": 256
  }

No I can specify pagination_page_size = 1 and offset_records_jsonpath = "$.contacts" to compare the correct number of records.

I added the optional argument offset_records_jsonpath to both top-level and stream level options.